Tinian Defense Forces

Japanese military fortification of Tinian and other islands in the chain had begun—in violation of the League of Nations Mandate—in the 1930s. By 1944, the Tinian garrison numbered roughly 9,000 army and navy personnel, bringing the island's total population to nearly 25,000.

The 50th Infantry Regiment, detached from the 29th Division on Guam, was the principal fighting force. It had been stationed near Mukden, Manchuria, from 1941 until its transfer in March 1944 to Tinian. Many of its troops were veterans of the Manchurian campaigns. The regiment was commanded by Colonel Kiyoshi [also spelled "Keishi"] Ogata and consisted of three 880-man infantry battalions, a 75mm mountain artillery battalion equipped with 12 guns, engineer, communication, and medical companies, plus a headquarters and various specialized support units, including a company of 12 light tanks and an anti-tank platoon. He also had a battalion of the 135th Infantry Regiment with a strength of about 900 men. Altogether, slightly more than 5,000 army troops were assigned to the island's defense.

The principal navy unit was the 56th Naval Guard Force, a 1,400-man coastal defense unit, supplemented by four construction battalions with a combined strength of 1,800 men. Other naval units, totaling about 1,000 men, included ground elements of seven aviation squadrons and a detachment of the 5th Base Force.

The navy personnel—about 4,200 altogether—were under the immediate command of Captain Oichi Oya. Both Oya and Ogata were outranked on the island by Vice Admiral Kakuji Kakuda, commander of the 1st Air Fleet with headquarters on Tinian. But Kakuda, as the invasion neared, had no air fleet to command. Of the estimated 107 planes based at Tinian's air fields, 70 had been destroyed on the ground early in June by U.S. air strikes. By the time of the Tinian landing on 24 July, none of Kakuda's planes were operative.

Kakuda had a bad reputation. He was, by Japanese physical standards, a hulking figure: more than six feet tall, weighing more than 200 pounds. "He willingly catered," Hoffman wrote, "to his almost unquenchable thirst for liquor; he lacked the fortitude to face the odds arrayed against him at Tinian." Historian Frank Hough called him "a drunk and an exceedingly unpleasant one, from all accounts."

On 15 July, nine days before the invasion, Kakuda and his headquarters group attempted to escape via rubber boats to Aguijan Island where they hoped to rendezvous with a Japanese submarine. This effort failed. He tried again on five successive nights with the same results, finally abandoning the effort on 21 July. He fled with his party from Tinian Town to a cave on Tinian's east coast where they awaited their fate. A Japanese prisoner who described Kakuda's escape efforts assumed he had committed suicide after the American landing, but this was never verified. Toward the end of the battle for Tinian, one of Kakuda's orderlies led an American patrol to the cave. The patrol was fired upon and two Marines were wounded. A passing group of Marine pioneers sealed the cave with demolition charges but it is unknown whether Kakuda was inside.

Admiral Kakuda in any case took no part in directing the Japanese resistance. For purposes of defending the island, command of both army and navy forces was assumed by Colonel Ogata, but co-operation between the two service branches was less than complete. Frictions were reflected in diaries found among the Japanese documents captured on Tinian. A soldier in the 50th Regiment's artillery battalion wrote:

9 March—The Navy stays in barracks buildings and has liberty every night with liquor to drink and makes a big row.

We, on the other hand, bivouac in the rain and never get out on pass. What a difference in discipline!

12 June—Our AA guns [manned by the Navy] spread black smoke where the enemy planes weren't. Not one hit out of a thousand shots. The Naval Air Group has taken to its heels.

15 June—The naval aviators are robbers . . . When they ran off to the mountains, they stole Army provisions . . . .

The defenses of Tinian were dictated by the geography of the island. It is encircled by coral cliffs which rise from the coastline and are a part of the limestone plateau underlying the island. These cliffs range in height from 6 to 100 feet; breaks in the cliffline are rare and where they occur are narrow, leaving little beach space for an invasion force. Along the entire coastline of Tinian, only four beaches were worthy of the name.

The largest and most suitable for use by an amphibious force was in front of Tinian Town in Suharon Harbor. It consisted of several wide, sandy strips. The harbor was mediocre but provided in fair weather limited anchorage for a few ships which could load and unload cargo at two piers available at Tinian Town.

From the beginning, Colonel Ogata assumed that this beach would be the first choice of the Americans. Of the roughly 100 guns in fixed positions on the island—ranging from 7.7mm heavy machine guns to 6-inch British naval rifles—nearly a third were assigned to the defense of Tinian Town and its beaches and to the airfield at Gurguan Point, two-and-a-half miles northwest of the town. Within a two-mile radius of the town were the 2d Battalion of the 50th Infantry Regiment, 1,400 men of the 56th Naval Guard Force, a tank company of the 18th Infantry Regiment, and the 1st Battalion, 135th Infantry Regiment, which had been designated as the mobile counterattack force.

Their area of responsibility extended to Laslo Point, the southernmost part of the island and, on the east, to Masalog Point. It was designated the "Southern Sector" in Ogata's defense plan.

The remainder of the island was divided into northeastern and northwestern sectors. The northeastern sector included the Ushi Point airfields and a potential landing beach 125 yards wide south of Asiga Point on the east coast of the island. In this sector, between 600 and 1,000 navy personnel were stationed around the Ushi Airfields. The 2d Battalion of the 50th Infantry Regiment, along with an engineer group, was stationed inland of Asagi Point. The northwestern sector contained two narrow strips of beach 1,000 yards apart. One of them was 60 yards wide and the other about 160. They were popular with Japanese civilians. The sand was white and the water was swimmable. They were known locally as the White Beaches and that is what they were called when they were chosen—to the great surprise of the Japanese—as the American invasion route.

This sector was defended very modestly by a single company of infantry, an antitank squad, and, about 500 yards northeast of the White Beaches, gun crews situated in emplacements containing one 37mm antitank gun, one 47mm antitank gun, and two 7.7mm machine guns.

Ogata established his command post in a cave on Mount Lasso in the center of the northern region, roughly equidistant—a little over two miles—from beaches on either side of the island.

He issued on 25 June an operation order saying "the enemy on Saipan can be expected to be planning a landing on Tinian. The area of that landing is estimated to be either Tinian Harbor or Asiga Harbor [on the northeast coast]." Three days later he followed up with a "Defense Force Battle Plan" which outlined only two contingencies:

(A) In the event the enemy lands at Tinian Harbor.

(B) In the event the enemy lands at Asiga Bay.

On 7 July Ogata issued a "Plan for the Guidance of Battle" ordering his men to be prepared not only for landings at Tinian Town and Asiga Bay, but also for a counterattack in the event the Americans were to invade across the White Beaches.

In each of the three sectors, according to his battle plan, commanders were to be prepared to "destroy the enemy at the beach, but [also] be prepared to shift two-thirds of the force elsewhere." His reserve force was to "maintain fortified positions, counter-attack points [and] maintain anti-aircraft observation and fire in its area." The "Mobile Counterattack Force" must "advance rapidly to the place of landings, depending on the situation and attack." In the event of successful landings his forces would "counterattack to the water and . . . destroy the enemy on beaches with one blow, especially where time prevents quick movement of forces within the island." If things were to go badly, "we will gradually fall back on our prepared positions in the southern part of the island and defend them to the last man."

Some of these orders were contradictory and others were impossible of execution. But despite the odds against them—bereft of air or sea support and confronted by three heavily armed divisions only three miles away on Saipan—the fighting spirit of the Japanese forces had not been broken by 43 days of the heaviest bombardment, up to then, of the Pacific war. One of the men of the 50th Infantry Regiment wrote in his diary on 30 June: "We have spent twenty days under unceasing enemy bombardment and air raids but have suffered only minor losses. Everyone from the Commanding Officer to the lowest private is full of fighting spirit." His entry for 19 July, five days before the American landings, was upbeat: "How exalted are the gallant figures of the Force Commander, the Battalion Commander, and their subordinates, who have endured the violent artillery and air bombardment."