Preliminary Bombardment Field Artillery : The decision to land the assault infantry troops across beaches on northwestern Tinian had stemmed in part from a desire to make optimum use of artillery based on Saipan. In many Pacific landings such as those at Tarawa, Saipan, and Iwo Jima it had not been, or was not to be, practicable to seize neighboring islands for the purpose of establishing bases for field artillery before the principal landing operations. Hence reliance had to be put entirely on naval gunfire and aircraft for whatever preliminary bombardment was laid down. In these operations some part, and probably a considerable part, of the casualties incurred by the infantry during the amphibious assault phase must be attributed to the limitations inherent in naval and aerial bombardment. The invasion of Tinian, on the other hand, offered an ideal opportunity to supplement these arms with field artillery. Tinian was, in fact, favored with a more prolonged preliminary artillery bombardment than any other island in the Central Pacific to be assaulted by American troops.
As early as 20 June, Battery B of the 531st Field Artillery Battalion was ordered to emplace its 155-mm. guns to fire on Tinian, Lateral observation posts were established on southern Saipan and counterbattery and destructive fires commenced forthwith. Four days later the battalion’s other two batteries, relieved of their duties of supporting the troops on Saipan, turned around and began firing to the south. On 8 July, the day before Saipan was declared secured, the other three battalions of XXIV Corps Artillery were ordered either to turn around in their present positions on southern Saipan or to displace to the area of Agingan Point and commence firing on Tinian. [N3-13-1 the field artillery battalions were the 225th (155-mm. howitzers), the 145th (105-mm. howitzers), and the 532nd (155-mm. guns).] Meanwhile, observation planes made daily flights over Tinian to register fires and to accumulate intelligence data for future use. Observation posts had been established on Agingan Point, Obiam Point, and Nafutan Point. Altogether, from 20 June through 9 July, while the troops were engaged in capturing Saipan, XXIV Corps Artillery fired a total of 331 missions—7,571 rounds—on Tinian, or roughly a fifth of the total it expended on Saipan. [N3-13-2 XXIV Corps Arty Final Rpt on FORAGER Opn, Phases I and III, S-2 Rpt, p. 8; Ibid., S-3 Rpt, pp. 7-8.]
With Saipan officially secured on 9 July, even greater attention could be directed toward the island to the south. Corps artillery increased the tempo of its bombardment. By 15 July all four battalions of the 27th Division artillery had displaced to new positions to fire on Tinian, as had also the two Marine divisions’ howitzers (except for the two 75-mm. pack howitzer battalions of each) [N3-13-4 Each Marine division had two 105-mm. howitzer battalions and two 75-mm. pack howitzer battalions.] and the 5th Battalion, V Amphibious Corps Artillery. This represented a total of 156 pieces—two 155-mm. gun battalions, three 155-mm. howitzer battalions, and eight 105-mm. howitzer battalions. Corps artillery had at its disposal nine organic planes plus the additional observation planes of the units attached. Air activity became so heavy at Isely Field that a new airstrip for the exclusive use of observation planes had to be constructed somewhat to the westward. Except for a brief period on 16-17 July, when ammunition ran low, artillery maintained a steady round-the-clock schedule of fire totaling 1,509 missions or 24,536 rounds. In addition to counterbattery and harassing and general area bombardment, the artillery attempted to burn off cane fields with white phosphorus shells, but without much success because of the heavy rains that immediately preceded the landing.
For the most part, XXIV Corps Artillery confined its efforts to the area north of the line between Gurguan Point and Masalog Point, while aircraft restricted their efforts to the southern half of the island. Naval ships were assigned any targets on Tinian deemed unsuitable to either of the other two arms. Co-ordination of the three supporting arms was assigned to the corps artillery representative attached to General Schmidt’s staff. In one instance, an artillery air observer discovered three 140-mm. coastal defense guns on Masalog Point that were within easy firing range of White Beaches 1 and 2, but were masked from field artillery. The battleship Colorado was called in and, with its main batteries adjusted by an airborne artillery observer, succeeded in neutralizing or destroying the enemy weapons. Because the spotting plane was not in direct radio contact with the ship, it was necessary for the plane to submit its spotting data to the artillery post by radio, whence they were relayed by telephone to General Schmidt’s headquarters, and in turn by radio on another frequency to the firing ship. In spite of this somewhat complicated system of communications, the time lag was so slight as to be insignificant.
Naval and Air Bombardment
Naval guns had harassed Tinian intermittently since 11 June when Admiral Mitscher’s Fast Carrier Force first made its appearance in the adjacent waters. For about a week after Saipan was secured, the job was left almost entirely to field artillery except for night fires delivered on Tinian Town by small naval craft. Then, starting on 15 July, naval gunfire was resumed. Admiral Hill’s plan called for daily destructive fire by destroyers on specific targets that were not suitable to air or artillery, gradual intensification of daytime fire by employment of additional destroyers and cruisers, and a continuation of night harassing missions. Commencing on the 16th, seven destroyers began to deliver destructive fire against targets designated by corps artillery.
On the evening of the 17th, additional destroyers commenced harassing fire against the Japanese who were known to be working feverishly at night to install beach defenses in the Asiga Bay area. On the 20th the cruiser Louisville was added to the armada, and two days later another cruiser, New Orleans, was sent into the line, as were two LCI gunboats whose job it was to pour 40-mm. fire into the many caves that pocked the cliffs along the shore line.
Starting at 0600 on 23 July, the day before the landing, Admiral Hill stepped up his preparatory fire with a total of three old battleships, two heavy cruisers, three light cruisers, and sixteen destroyers, distributed in such a way that the island of Tinian would be shelled from every point on the compass. The Navy made no effort to concentrate on White Beaches 1 and 2—in fact, the ships assigned to that area were fewer in number than in most of the other five sectors into which the waters off the island were subdivided. Deception was given even greater consideration than destruction, and the naval gunfire plan can have given the Japanese no indication as to where the amphibious assault would take place. At 1500 all ships ceased fire for an hour to permit aircraft to drop napalm bombs on the wooded area inland of Faibus San Hilo Point, and at 1720 naval fire was again discontinued for an air strike with napalm against the White Beaches area. During the night of 23-24 July destroyers and cruisers kept important road junctions between Faibus San Hilo and Gurguan Points interdicted, while the destroyer Norman Scott delivered harassing fire to cover Asiga Bay and all important road junctions on the east side of the island.
Another destroyer, Waller, covered a last-minute underwater reconnaissance of White Beaches 1 and 2 by Underwater Demolition Team 5, which unsuccessfully attempted to detonate some recently discovered mines. Throughout the day and thereafter during the operation, in order to minimize interference between air and naval gunfire, all ships were directed to deliver their fire from ranges of a maximum ordinate of less than 1,000 feet when possible and to exceed that maximum only after notification by Admiral Hill.
For air support on Tinian, Commander Lloyd B. Osborne, USN, who was Admiral Hill’s Commander, Northern Support Aircraft, had 358 fighters, bombers, and torpedo planes under his control, mostly Army and Navy. Tinian, like Saipan, had of course felt the might of Marc Mitscher’s carrier force early in June, and from then on was subject to an increasing tempo of bombing from naval planes of Turner’s and Hill’s escort carriers and from Army P-47’s from Isely Field. Starting on 22 June, P-47’s of the 318th Fighter Group kept the airfields at Ushi and Gurguan Point and the new strip just east of Tinian Town under constant strafing and bombing attacks. Tinian Town itself was reduced to rubble.
On 22 July, just two days before the invasion, two P-47’s dropped on Tinian the first napalm bombs used in the Pacific war. These were fire bombs consisting of jettison able aircraft fuel tanks filled with a mixture of napalm gel and gasoline.
Shortly before the scheduled landing on Tinian, Lt, Comdr. Louis W. Mang, USNR, recently arrived from the United States, easily persuaded Admiral Hill of the efficacy of these new bombs, and, since napalm was in short supply, an order for 8,500 pounds was immediately dispatched to Pearl Harbor. Meanwhile, diesel oil was sometimes used as a less efficient substitute. The new fire bombs were found to be especially effective in burning cane fields and underbrush. During the late afternoon of 23 July thirty were dropped immediately inland and on the flanks of White Beaches 1 and 2 to burn off underbrush cover and destroy enemy personnel that might be located in open trenches and dugouts. In both respects the bombs were successful and their continued employment in the Pacific war was assured.
At daybreak on 24 July a motley flotilla of ships and landing craft carrying the 2nd and 4th Marine Divisions got under way from Tanapag Harbor for the short trip to Tinian. Altogether, it included 8 transports, 37 LST’s, 2 LSD’s, 31 LCI’s, 20 LCT’s, 92 LCM’s, 100 LCVP’s, 533 LVT’s, and 140 DUKW’s. All of the LST’s were assigned to the 4th Marine Division, whose assault troops were nested in their amphibian tractors waiting for the moment when the bow doors would open and their vehicles would crawl out into the water and approach their line of departure. Four of the LST’s carried DUKW’s, aboard which had been loaded four battalions of 75-mm. pack howitzers. Tanks were stowed in LCT’s and LCM’s, some to be carried to their destination in the wells of LSD’s, others to get there under their own power. The eight transports carried the two regimental combat teams of the 2nd Marine Division scheduled to make a diversionary feint at Tinian Town before landing in the rear of the assault troops. The division’s other regiment would have to stand by on Saipan until ten of the LST’s bound for White Beaches 1 and 2 had unloaded and returned to pick it up.
On past the White Beaches to Sunharon Bay steamed the Demonstration Group— the transports carrying the two 2nd Marine Division RCT’s accompanied by their escorts. [N3-13-12] The Japanese expected a landing at Tinian Town, and Admiral Hill intended to prolong that expectation as far as possible. Into the water went landing craft lowered from their mother transports; down the cargo nets climbed the marines of the 2nd Division, to all appearances bound for the beach.
Ashore, the Japanese reacted immediately and furiously. Flashes from their guns, followed by tremendous geysers of water, kept the marines crouching low beneath the gunwales of their boats as they approached the 2,000-yard line, which marked the inshore limits of their fake attack.
Nothing but water and a few shell fragments hit the troops, but the escorting ships were not so lucky. The three British-made 6-inch coastal defense guns located south of Tinian Town struck the battleship Colorado and the destroyer Norman Scott, scoring twenty-two hits on the former and six on the latter. In this short action the Navy lost 62 killed and 245 wounded before the shore battery could be silenced.[N3-13-13] By 1015 the boats and men had been recovered and the Demonstration Group stood up the coast toward White Beaches. The feint had been altogether successful.
From Colonel Ogata to Tokyo went the message that more than a hundred landing barges had been repulsed in an attempt to get ashore at Tinian Town. The 56th Naval Guard Force stuck to its guns that guarded Sunharon Bay, and no part of the 3rd Battalion, 50th Infantry Regiment, abandoned the southern sector to meet the amphibious landing in the north. One Japanese infantryman probably reflected the thoughts and hopes of all when he wrote in his diary, “24 July: Today the enemy began to land on the beach at Tinian. 3 companies were sent out. Our platoon moved into position. . . . Up to 0900 artillery fire was fierce in the direction of Port Tinian but it became quiet after the enemy warships left. Maybe the enemy is retreating.”
[N3-13-12 Unless otherwise noted, the account of the diversionary feint against Tinian Town is derived from TF 52 Rpt Tinian, pp. 30-32; Hoffman, Tinian, pp. 43-45; Morison, New Guinea and the Marianas, pp. 361-62. ]
[N3-13-13 The battery was actually destroyed four days later by the battleship Tennessee. Morison, New Guinea and the Marianas, p. 362. ]
Meanwhile, the northwest coast of Tinian which had heretofore been treated with a studied impartiality, began to receive the full force of the attackers’ armament. At 0600 one battery of 155-mm. howitzers on Saipan commenced laying down a smoke screen on Mount Lasso to last for two and a half hours. Forty-five minutes later all of General Harper’s guns and howitzers burst forth in a massed fire. For fifteen minutes artillery pounded known installations on northern Tinian, likely enemy assembly areas, and avenues of approaches to the beaches. Then, on signal, artillery lifted its fires to the woods and bluffs above the shore from which the Japanese might observe the approach of the assault craft and vehicles.
The chorus of destruction was swelled by Admiral Hill’s support ships offshore. Starting at 0530, Tennessee, California, and Louisville opened up on White Beaches 1 and 2 with their main batteries, while Birmingham and Montpelier together bracketed Mount Lasso from opposite sides of the island. Freshly arrived from Guam, Admiral Spruance’s flagship Indianapolis took over responsibility for Faibus San Hilo Point, which overlooked the landing beaches from the south. From 0625 until 0640 all ships’ fire ceased in order to allow an air strike against the beaches, and more particularly against the recently discovered mines off White Beach 2, which neither underwater demolition swimmers, nor mine sweepers, nor ships’ guns had been able to detonate. Thirty minutes before the scheduled landing time, artillery fire from Saipan shifted to the landing beaches. Throughout this period, one battery of 155-mm. howitzers fired a continuous barrage of smoke shells at Mount Lasso to prevent enemy observation of the landing beaches. Then came the final crescendo of naval bombardment with destroyers abandoning their screening duties to add their five-inch shells to the general destruction.
The first wave was to touch down at 0730, but because of a slight delay in forming the landing waves, Admiral Hill ordered a ten-minute postponement. The formation of landing craft and vehicles followed the pattern by now familiar in the Central Pacific. First in line abreast went the LCI gunboats, six toward White Beach 1, nine toward White Beach 2. Astern came a wave of amphibian tanks, followed in turn by the troop-carrying amphibian tractors. Those bound for the northern landing beach were crewed by marines of the 2nd Amphibian Tractor Battalion; the Army’s 773rd Amphibian Tractor Battalion carried the assault troops to the southern beach. As the gunboats approached shallow water, they turned to port and starboard and took the flanks of the landing area under fire; at 300 yards the amphibian tanks turned toward the flanks and the first waves of amphibian tractors churned through the water to touch shore on White Beach 1 at 0742, on White Beach 2 at 0750.
By comparison with most assault landings in the Central Pacific, the initial invasion of Tinian was easy. Within forty minutes after the touch down, the entire assault battalion of the 24th Marines was ashore on White Beach 1, and after a brief fire fight moved rapidly to the first objective line. On White Beach 2, to the south, the 25th Marines faced somewhat heavier odds in the form of scattered land mines and two Japanese pillboxes undestroyed by the preliminary bombardment. Two LVT’s were blown up by the mines. As the first wave of marines rushed inland it bypassed the pillboxes, which were subsequently reduced without difficulty. Following the landing of the two assault regiments, tanks and half-tracks moved in on schedule, and in spite of the difficulties involved in landing over the narrow, cliff-flanked beaches, none of the vehicles was lost. By midafternoon DUKW’s had succeeded in landing all four of the pack howitzer battalions assigned to the 4th Marine Division, and by late afternoon the reserve regiment (23rd Marines), after some delay caused by communications failure, was ashore and in position in its assembly area on the right (south) flank of the beachhead. The two shore parties (1341st Engineer Battalion (Army) on White Beach 1 and the 2nd Battalion, 20th Marines, on White Beach 2) had landed all their men and equipment by 1400. Two of the ten special portable LVT ramps were launched late in the afternoon. One capsized when the amphibian tractor struck a coral head, but the other was in proper position before nightfall. Six of the eight remaining ramps were installed the next day, the other two having been swamped in the process.
By nightfall of the 24th the 4th Marine Division had established a beachhead about 2,900 yards in width and almost a mile deep in the center. Casualties for the day had been light—15 killed and 225 wounded. Barbed wire was strung along the entire length of the division front, machine guns were emplaced to provide interlocking bands of fire, and pack howitzers were registered to cover the main road from Ushi Point airfield and other likely routes of enemy approach. Amphibian vehicles preloaded with ammunition had made their direct deliveries from ships lying offshore to the front-line troops as scheduled, and the latter were well supplied with reserve stocks of shells, mortars, and bullets. Every precaution was taken against the expected traditional first-night enemy counterattack. When it came, the marines were ready for it.
Japanese Counterattack 24-25 July
Having failed to stem the tide of the American assault over the beaches, Colonel Ogata now had to put into execution the second phase of his defensive plan—an organized counterattack during the first night after the landing. Whether the Japanese commander was in direct communication with any of his troops other than those assigned to the Tinian Town area is uncertain, but his battalion commanders were well enough indoctrinated to launch the drive on their own initiative. Still under the illusion that the main amphibious assault would eventually be directed against Tinian Town, Ogata kept the 3rd Battalion, 50th Regiment, in position. The 2nd Battalion, to which had been assigned the northeast sector guarding Asiga Bay, also stayed out of the fight, as did the main body of the 56th Naval Guard Force manning the coastal defense guns along southern Tinian. Thus the brunt of the counterattack fell to Ogata’s mobile reserve battalion (the 1st Battalion, 135th Infantry Regiment), the 1st Battalion, 50th Infantry, and sundry naval units stationed in the northern part of the island.[N3-13-22]
The attack, when it came, consisted of three separate and seemingly un-coordinated thrusts against the American front—one along the western shore against the marines’ left, one in the, center at the boundary between the 25th and 24th Marines, and a third against the 23rd Marines on the American right flank. The first commenced about 0200 and was undertaken exclusively by naval personnel coming down from the north. It lasted almost five hours, but the Japanese failed to penetrate the marines lines at any point and lost an estimated 476 men in the effort. [N3-13-23]
In the center, Japanese infantrymen struck about 0230. Between the two Marine regiments they discovered a weak spot in the line through which a large body of Japanese poured and then branched out in two directions. One of the enemy groups turned west toward the rear areas of the 25th Marines where it was eliminated after a brief fire fight. The other headed straight for the beach where it was eventually stopped by Marine artillerymen and elements of the 2nd Marine Division that had landed only a few hours earlier. The next morning almost 500 dead Japanese were counted in this area.
The third attack was from the south and was preceded by five or six tanks, over half of the entire Japanese tank strength on the island. All the tanks were destroyed before they penetrated the lines of the 23rd Marines, against which the attack was directed. The infantrymen following the tanks had no better luck. In the eerie light furnished by naval star shells, the marines quickly disposed of this last group, estimated to number over 270 enemy soldiers.
On the morning of the 25th a total of 1,241 Japanese dead was counted, about 700 identified as members of the two infantry regiments. Later interrogation of six prisoners of war revealed that by the morning of the 25th the 1st Battalion, 50th Infantry, had been virtually destroyed as a result of the fighting incident to the landing and the counterattack. Another prisoner of war testified that the 1st Battalion, 135th Infantry, Ogata’s mobile reserve, had been “practically annihilated.” In the light of this evidence, General Cates’ final conclusion seems irrefutable—in the early morning hours of 25 July, the 4th Marine Division “broke the Japs back in the battle for Tinian.”
[N3-13-22 The account of the counterattack is derived from 4th Marine Div D-2 Periodic Rpt 72, and Hoffman, Tinian, pp. 62-68.]
[N3-13-23 This and subsequent figures for Japanese casualties are taken from dead counts made on the morning of 25 July. Since some of the Japanese may have been killed by preliminary naval, air, and artillery fire, the estimates are probably exaggerated.]
Capture of Northern Tinian
During the next eight days, until the island was finally declared secured on 1 August, the fighting on Tinian resolved itself into three phases. First, it was necessary to push across to the eastern coast and seal off the entire northern third of the island, including such vital points as Mount Maga, Mount Lasso, and the Ushi Point airfield. Once this was accomplished, both Marine divisions could wheel to the south and proceed at a more rapid pace down Tinian’s long axis until they reached the foot of the plateau that dominated the island’s southern tip. Finally came the two day battle for the plateau and the cliffs of Marpo Point that brought the operation to a close.
On 25 July the 4th Marine Division, against only sporadic resistance, spent the day expanding the beachhead in all directions.
On the right, the 23rd Marines covered about half the distance from White Beach 2 to Faibus San Hilo Point, meeting very few Japanese as they went. In the center, the 25th and 24th Regiments made comparable advances in an easterly and southeasterly direction, the 25th capturing Mount Maga, which lay athwart the division’s approaches to Mount Lasso, the highest point of the island. Army P-47’s flying from Isely Field, as well as artillery based on Saipan, supported the action. On the left, the 8th Marines (attached to the 4th Marine Division), assisted by tanks and by armored amphibians firing from the water, inched its way through the coral cliffs that lined the west coast north of White Beach 1. Meanwhile, most of the remainder of the 2nd Marine Division had come ashore and by midafternoon General Watson had set up his command post inland of White Beach 2.
Marine casualties for the day were low, and enemy opposition, although occasionally fierce, was spotty. Nevertheless, those marines who did make contact with the enemy developed a healthy respect for the caliber of the Tinian garrison. The Japanese here were reported “to be better troops than those encountered on Saipan, with much better marksmanship.”
The fact is that immediately after the failure of his night counterattack, Colonel Ogata decided to disengage his forces and establish a new defense line running from Gurguan Point to the radio station inland from the center of Asiga Bay. The brief flurry of artillery fire that the 25th Marines had encountered during their approach to Mount Maga had merely been a delaying action. The bulk of the Japanese troops remaining in northern Tinian were withdrawing to the new line south of Mount Lasso.
On JIG plus 2 (26 July) General Schmidt ordered the 4th Division now on the right to continue the attack in a southerly direction and the 2nd Division to drive straight toward the east coast. In the 4th Division zone, the 23rd Marines pushed down the coast another 2,500 yards to a point well below Faibus San Hilo Point, while the 25th Marines occupied Mount Lasso, which had been entirely evacuated by the Japanese the day before. At Mount Lasso the 25th Marines reported evidence of “a careful, well-planned withdrawal, removing dead and destroying documents. Abandoned positions had been well dug-in and carefully planned.”
On the corps left, meanwhile, the 8th Marines took over Ushi Point airfield, and its sister regiments sped on to the east coast and prepared to swing south.Thus, in three days, the major tactical objectives of the Tinian invasion had been achieved: Ogata’s major counterattack had been beaten off with a consequent loss to him of about one fourth of his force; Ushi Point airfield had been taken and was already in the process of being made operational for American planes; Mount Lasso, the commanding position of the island had been occupied. In the words of the official Marine Corps historian, “Seldom was the victor of any of the Central Pacific conquests so unmistakably identified so early in the fight.”
Drive to the South
From 27 through 30 July both Marine divisions made rapid advances toward the plateau that dominated the southern tip of the island. Enemy resistance on the 27th and 28th was almost nonexistent, but it gradually stiffened as the Americans approached the Japanese last main defensive line. During the 27th and 28th General Schmidt employed what has been called an “elbowing” technique. That is, on the first day of the attack southward, he held back the 4th Division on the right while the 2nd Division surged forward; the second day which permitted rapid advance toward the hill mass that dominates the southern tip of the island. Purpose of this tactic was to permit his artillery to concentrate first in support of one division, then of the other.
On the 29th this technique was abandoned, and both divisions were ordered to advance as rapidly within their respective zones as conditions permitted.36 On the right, the 4th Division on the 30th assaulted a series of well-camouflaged cave positions on the west coast and after reducing them pushed on in and through Tinian Town. Land mine fields on the town’s outskirts and along the beaches of Sunharon Bay slowed the advance a little, but the town itself had been reduced to rubble by naval gunfire and aerial bombardment and had been evacuated. On the left, the 2nd Division faced a tougher proposition as it came abreast the Masalog hill mass, but by nightfall of the 30th the area was overrun, and the Japanese were in retreat to the south.
Apparently Colonel Ogata had relinquished his mid-island line of defense almost as soon as it had been established, and on the night of the 29th he moved his command post to a shrine in a cliff near Marpo Point. Seeing his delaying actions crumble before the advancing Americans, he ordered all Army and Navy forces to assemble on the southern tip of the island to defend the ridge line there.
On their part, the Americans in four days had pushed their lines ahead about 10,000 yards on the left and 4,000 on the right. Coming so soon after the prolonged deadlocks of the Saipan battle, this seemed indeed like a sprint. As General Cates expressed it, the marines were “heading for the barn.”
One of the reasons for this rapid movement was the gently undulating terrain of central Tinian, which permitted tanks to be used with far greater effectiveness than had been the case on Saipan. To each regiment was assigned one reinforced medium tank company (eighteen tanks), a platoon of four flame thrower tanks, and two light tanks. Each of the tank companies stayed with its parent regiment throughout the operation, which of course facilitated tank-infantry co-ordination. Also, one infantry regiment of each division was at all times in reserve, thus giving its assigned tank unit an opportunity to repair its vehicles. In addition, communications between tanks and infantry were markedly improved over those on Saipan.
Tinian’s terrain also offered more favorable opportunities for the employment of artillery than had Saipan’s. Initially, all artillery in support of the 4th Marine Division was based on Saipan except for four battalions of 75-mm. pack howitzers from the 14th and 10th Marine Artillery Regiments. On 26 July the 3rd Battalion, 14th Marines (105-mm. howitzers), came ashore, followed the next day by the 105-mm. howitzers of the 4th Artillery Battalion, V Amphibious Corps (attached to the 4th Marine Division), and the two 105-mm. howitzer battalions of the 10th Marines.
On 28 July the 419th Field Artillery Group of the XXIV Corps Artillery (155-mm. howitzers) displaced from Saipan to positions on Tinian, as did one battery of the 106th Field Artillery Battalion (also 155-mm. howitzers). The other two batteries of this battalion were forced to return to their Saipan positions since they were unable to land over the White Beaches because of wrecked pontoon causeways there. The XXIV Corps Artillery’s 420th Field Artillery Group remained on Saipan throughout, its 155-mm. guns having sufficient range to hit any part of the southern island.
Corps artillery alone fired 1,404 missions, totaling 46,309 rounds, during the assault and capture of Tinian.45 Added to this, of course, was the Marine divisions’ organic artillery, which fired approximately 142,000 additional rounds. As one Japanese prisoner testified, “You couldn’t drop a stick without bringing down artillery.”
Close air support on Tinian was provided by Army P-47’s flying from Isely Field, as well as Navy carrier-based planes. As the two Marine divisions started their drive south from the Mount Lasso line, Army and Navy aircraft alternated in providing air cover in advance of the troops, averaging 175 sorties daily. Admiral Hill’s support aircraft commander, Commander Osborne, had the final responsibility for approving and directing all air strikes requested by the Marines on the front line.
Under him was the Commander, Support Aircraft Ashore, who was stationed on Isely Field with authority to exercise direct control over the P-47’s. Final responsibility for co-ordinating air, artillery, and naval bombardment resided with a representative from XXIV Corps Artillery at General Schmidt’s headquarters.
Only in rare instances were supporting aircraft directly coached into their targets by air liaison parties attached to the infantry. The Navy command was fearful of turning over control of supporting aircraft to the ground troops for a variety of reasons. Neither the air liaison parties nor the pilots were deemed sufficiently trained in the niceties of air-ground co-ordination to risk it. Air-ground communications were uncertain chiefly because of unsatisfactory and insufficient radio equipment. Finally, the danger of decentralizing control of air strikes over such a small target as Tinian was considerable. Once the drive to the south was under way, the marines had on the front lines at all times at least twelve battalions, each with its own air liaison party. The lines themselves were often irregular and of course the front narrowed as the troops approached the southern tip of the island. Under these conditions, to have allowed each battalion to control its own called strikes would have seriously endangered the units on the flanks, and the risk was considered unacceptable. On Tinian, as on Saipan, the time lag between requests for and execution of air strikes was a cause for dissatisfaction among the ground troop commanders.
Even when the planes were on station above the target, half an hour was usually required to complete an air strike, and when the planes had to be flown from their mother carriers or from Isely Field, an hour’s delay was more common. One air liaison party had to wait a full nineteen hours to get its request honored, but that was exceptional. Nevertheless, General Cates and General Watson were both of the opinion that the execution of air strikes was several cuts above what it had been on Saipan—largely because the pilots had been better briefed, were more familiar with the terrain, and were gaining experience.
Naval fire support during the battle for Tinian was also considered to be an improvement over that for Saipan, again because of greater experience on the part of ships’ companies and because of more favorable terrain. Preparation fires were commonly delivered on request of division commanders before the morning jump-off to supplement the field artillery, and counterbattery interdiction and destructive fires were delivered daily on call. In the opinion of Lieutenant Colonel E. G. Van Orman, USMC, who was Holland Smith’s naval gunfire officer, “In the occupation of Tinian call fire procedure was carried out much more satisfactorily than at either Saipan or Guam because of experience gained by all hands at Saipan and exchanged and clarified in meetings of all personnel both afloat and ashore prior to J-Day.”
Perhaps the most unusual features of the battle for Tinian were the techniques that were improvised for getting supplies over the narrow beaches to the front-line troops both during the initial amphibious phase and later. Responsibility for preparing the beaches themselves and for controlling traffic over them fell to the Army’s 1341st Engineer Battalion and the 2nd Battalion, 20th Marines (the Engineer regiment of the 4th Marine Division). The former was assigned to White Beach 1, the latter to White Beach 2. Both were landed on JIG Day, at first operating under control of the 4th Marine Division and later (26 July) coming under the direct command of General Schmidt’s shore party officer, Colonel Cyril W. Martyr, USMC. Also on the 26th the 2nd Battalion, 18th Marines (organic to the 2nd Marine Division), came ashore to assist at White Beach 2, to work in the division dumps, and later to help unload aircraft at Ushi Point airfield.
To facilitate unloading on the White Beaches, two pontoon causeways were assembled on Saipan and on the afternoon of 24 July were towed to Tinian. There they were put to excellent use until the night of 29 July, when the tail of a typhoon that had been building up in the Philippine Sea hit Tinian with full force. The storm broached one of the artificial piers and broke the other in two.
It was during this typhoon that the DUKW’s once again demonstrated their outstanding versatility and durability. About half of the 140 amphibian trucks used on Tinian were crewed by Army personnel of the 477th Amphibian Truck Company and the 27th Division Provisional Amphibian Truck Company, the rest were crewed by marines of the 1st and 2nd Marine Amphibian Truck Companies. As the seas mounted on the afternoon of 29 July, broaching one LST and washing a landing craft control boat up on the beach, it developed that of all the small craft and vehicles present, only the DUKW’s were seaworthy enough to operate in the heavy swells, and for the duration of the storm they were solely responsible for overwater supply.[N3-13-57]
As General Schmidt’s supply officer remarked, the DUKW’s at Tinian “performed an astounding feat of supply.” Equipped with A-frames, they carried most of the artillery pieces from LST’s directly to firing positions ashore. [N3-13-59] They were solely responsible for averting a serious fuel shortage when the typhoon struck, since they were the only means at hand for getting through the surf to fuel barges anchored off the northwest coast of Tinian. Not only did they prove more seaworthy than their sister amphibian vehicle, the LVT, but over Tinian’s fairly well developed road system they delivered supplies more quickly to the troops as they approached the southern end of the island and also, of course, wrought much less damage to the roads than did the tracked vehicles.
The DUKW’s and LVT’s bore the main burden of shuttling supplies and equipment of all kinds from the vessels lying off the beaches straight to inland dumps, or even to the men on the front lines as they pushed farther southward. It was this direct and rapid system of supply, which eliminated manhandling supplies on the beaches that struck most observers as the outstanding feature of the Tinian battle. [N3-13-61]
In the words of General Schmidt’s supply officer: This operation was in many ways a remarkable demonstration of the fact that preconceived notions and amphibious doctrine can be altered radically on the spot. In effect, a reinforced corps was landed over less than 200 yards of beach and over a difficult reef, and was supplied throughout nine days of heavy combat without handling so much as one pound of supplies in the usual shore party manner. Everything rolled in on wheels. When a violent sea made impossible the landing of trucks, the DUKW’s took over all supply, supplemented to a minor degree by incoming air evacuation planes bringing in rations. The troops never lacked what they required at the time it was required.
[N3-13-57 NTLF Rpt Marianas, Phase III, Incl F, G-4 Rpt, Sec. B, pp. 2-3. To supplement this delivery, transport planes from Saipan flew rations to the front-line troops on Tinian]
[N3-13-59 This particular use of the specially adapted DUKW’s had been introduced by the 7th Infantry Division at the invasion of Kwajalein. See Crowl and Love, Gilberts and Marshalls, p. 227. 60 Hoffman, Tinian, p. 136.]
[N3-13-61 NTLF Rpt Marianas, Phase III, Incl F, Supply Rpt, p. 4. This statement contains two minor inaccuracies. The beaches were somewhat more than 200 yards in width, and the vehicles that carried supplies inland were tracked as well as wheeled.]
Nightfall of 30 July found the two Marine divisions drawn up on a line just north of the hill mass that dominated the southern tip of Tinian. South of them was about a mile of flat land that terminated in an abrupt wooded escarpment rising to a plateau. Here Colonel Ogata had elected to make his last desperate stand. The area consisted mostly of an oblong mountain mass about 5,000 yards long and 2,000 wide running generally in a northeast-southwest direction. This high ground was something like a huge mesa with the steep ridges and cliffs of its shoulders supporting the comparatively gentle slopes along the top. Of the two long sides, one faced the flat land around Tinian Town, the other met the sea on the east coast. The entire southern tip sloped steeply to the water. Colonel Ogata’s defense line was drawn on the forward (northwestern) slopes of the hill mass.
On the morning of 31 July the marines attacked as before with two divisions abreast, the 4th on the right, 2nd on the left. Before the jump-off, two battleships (Tennessee and California) and three cruisers (Louisville, Montpelier, and Birmingham) fired about 615 tons of shells into the area, and Army bombers dropped about 69 tons of explosives.
On the right the 24th Marines, supported by tanks and armored amphibians, made slow but steady progress against stiffening resistance along the coast line south of Tinian Town, and by the end of the day had advanced about 2,500 yards. The 23rd Marines on the division left faced greater obstacles as it came up against the cliff line that marked the northwestern face of the plateau. With the help of supporting tanks, the regiment knocked out a 47-mm. antitank gun in the path of its progress and at day’s end dug in at the foot of the cliff, though one company reached the top and spent the night there.
On the left, the 2nd Marine Division attacked with three regiments abreast. The two left regiments, 2nd and 6th Marines, moved forward to the base of the cliff against only light rifle and machine gun fire, but the 8th Marines was not let off so easy. In its zone lay the precipitous double-hairpin road that offered the most feasible route to the top of the plateau, and to get even partial command of this artery took a day of heavy fighting and arduous climbing. By late afternoon one company had reached the top of the cliff, followed after dark by most of the two assault battalions of the 8th Marines, but, as night fell, there was a gap of 600 yards on the right and one of 350 yards on the left of the Marine battalions atop the cliff. The time and the situation were ripe for a Japanese counterattack, and it came as expected.
Colonel Ogata personally led the counterattack, which was directed mainly against the 8th Marines atop the cliff. According to one Japanese prisoner of war, Ogata was killed during the charge by American machine guns and was last seen hanging dead over the Marines’ barbed wire. [N3-13-66] About 2300 the Japanese first struck elements of the 8th Marines but were repulsed. Three hours later a force of some 150 of the enemy suddenly rushed the hairpin road up which the marines had been trying to carry ammunition and other supplies. There, the Japanese set up a roadblock, burned two ambulance jeeps, and threatened to cut off the two American battalions on top of the plateau. An hour later a platoon of the enemy moved up the road and attacked from the rear. In a short but furious fire fight they were driven back and their roadblock was eliminated. For the next three hours, 75-mm. half-tracks, mortars, and field artillery kept the enemy at bay, but at 0515 came the final banzai charge. For a full half hour the attackers charged the Marine lines, but at no point did they penetrate. Daybreak revealed over a hundred enemy dead in an area only about 70 yards square. Later interrogation of prisoners indicated that the entire counterattacking force had numbered between six and eight hundred.
[N3-13-66 NTLF Rpt Marianas, Phase III, Incl D, G-2 Rpt, pp. 18, 20, 21. A Japanese study of the operation prepared after the war, on the other hand, has Ogata still alive and leading another counterattack as late as 3 August. Japanese Studies in World War II, No. 55, p. 53.]
With the failure of this last counterattack, organized Japanese resistance quickly came to an end. By late afternoon on 1 August both Marine divisions had reached the southern edge of the cliff line, and at 1855 General Schmidt declared the island secured. Mopping up, to be sure, was a long and often bloody process. [N3-13-69] Not until 1 January 1945 were the remnants of the enemy force considered sufficiently disposed of to permit the mop-up troops, the 8th Marines, to be transferred to Saipan. In the three months after Tinian was turned over to the island commander, Major General James L. Underhill, USMC, a total of 542 Japanese were reported killed.
[N3-13-69 Private First Class Robert L. Wilson of the 2nd Battalion, 6th Marines, was posthumously awarded the Medal of Honor for covering with his own body a live hand grenade on 3 August, two days after Tinian had been declared secured. For a similar feat performed on 30 July, Private Joseph W. Ozbourn, 1st Battalion, 23rd Marines, was given the same award. Hoffman, Tinian, pp. 98, 117.]
Altogether, the capture of Tinian had cost the invading ground forces a total of 328 killed and 1,571 wounded in action, almost all of them Marine Corps personnel. In exchange, the Japanese sacrificed their entire garrison of more than eight thousand men, most of them killed. More significant than this death toll was the fact that the U.S. forces had succeeded in wresting from the enemy one of the best airfield sites in the Central Pacific. Ushi Point airfield and Gurguan Point airfield, enlarged and expanded, became vital bases for the XXI Bomber Command, which in the spring and summer of 1945 would unleash its very long range bombers against the Japanese homeland with such devastating effect. Significantly, it was from Ushi Point airfield that the B-29 Enola Gay, took off on 6 August 1945 to drop the first atomic bomb on the city of Hiroshima.
Tinian was largely a Marine Corps show. A Marine headquarters made the tactical plans and Marine infantrymen carried the main burden of attacking and overrunning the island. Nevertheless, the Army’s role was by no means negligible. In the ship-to-shore movement, over half of the amphibian tractors were provided by the Army and crewed by soldiers. Half of the amphibian trucks that landed the artillery and later, during the typhoon, played such an important role in supplying the troops, were Army-manned. An Army engineer battalion acted as shore party for one of the landing beaches. Army artillery played a decisive part in the preliminary bombardment and in supporting the marines after they had landed. Finally, Army P-47’s flew continuous close support missions in front of the Marine infantry. Since so much of the success of the operation depended upon artillery based on Saipan, on the efficient work of the amphibian vehicles, on the organization of the supply system at the beaches, and on close air support, it can be concluded that the Army’s share in the reduction of Tinian was far out of proportion to the number of its personnel actually committed to the operation.
SOURCE: Campaign in the Marianas; BY: Philip A. Crowl (United States Army Center of Military History)