18th Infantry Regiment (Imperial Japanese Army)

After re-organization, two battalions of the under-equipped 18th Regiment were transported to Guam in May 1944;[7][9] however, about 600 troops of the 1st Battalion had to be left behind on Saipan. These troops, under Captain Masao Kubo, joined the island's garrison,[15] though nearly all would be killed during the Battle of Saipan in June and July 1944.[9] In the aftermath of the battle, Capt. Sakae Ōba distinguished himself by taking command of a number of soldiers and sailors who had survived the battle, as well as Japanese civilians who looked to him for guidance and protection. The group numbered about 300, and took shelter in caves or small villages in the jungle. They evaded capture by the U.S. Marines that were hunting for them, conducted harassment raids, and survived until they finally agreed to surrender on 1 December 1945.[16]

Map of Battle of Guam (1944).

In March 1944, the 29th Division commander, Lieutenant General Takeshi Takashina, landed on Guam and assumed overall command of all military units for the island's defense.[13] In preparation for the imminent invasion of Guam by Allied forces, the main body of the 18th Regiment was situated on a mountain, with each company deployed to cover possible landing points in support of the island's defensive strategy.[2] On 21 July 1944 the American landing operation commenced.[17] Despite fierce resistance, United States Army and Marine forces gained two beachheads by nightfall, straddling the Orote Peninsula on the west coast of the island, while the defenders either counterattacked or continued to fire on American positions with machine guns, artillery, and mortars.[18]

On 24 July, the command headquarters of the Japanese forces on Guam received word from Tokyo to "Defend Guam at all costs".[19] General Takashina devised a plan of attack to dislodge the 3rd Marine Division, which occupied the high ground at Asan, north of the Orote Peninsula. Takashina's attack would be coordinated with a breakout attempt of Japanese forces trapped on the peninsula.[19] The 18th Regiment, which had been reorganized into three battalions, was to be one of the main units to assault the American position. Two battalions would attack the 21st Marine Regiment and the other battalion was to attack the flank of the 9th Marines. The objective was to exploit an 800-yard gap between the two regiments, break through the American lines, and attain the high ground. Other units would attack the Marines or head to the beaches with demolition charges to destroy any ammunition or supply caches left by American forces.[20]

On the night of 25 July, the colors of the 18th Infantry Regiment were ritually burned, by authorization of the division commander, in anticipation of the regiment's complete destruction.[6]

Just after midnight, the 1st Battalion, 18th Regiment, attacked the center of the 22nd Marines. Veterans of the battle later reported that while many of the Japanese soldiers carried rifles and their officers led with swords, some of the Japanese carried knives, pitchforks, or their bayonets mounted to long sticks and used as spears. Charging across open ground, they were hit by American artillery, mortars, and machine gun fire until they retreated into a mangrove swamp. Artillery continued to bombard the swamps, discouraging further attack from that approach.[21]

The Japanese main attack was launched at about 0300, 26 July. The assault of the 2nd Battalion, 18th Regiment, under Major Maruyama Chusa, struck the center of the 21st Marines, and was the scene of some of the most desperate hand-to-hand combat of the entire night.[22] The battalion charged through machine gun and artillery fire in an effort to reach the Marines. In an effort to break through the lines, Maruyama's men fought their way into a draw that led down to the beach. The Marines had prepared for that possibility, and once in the draw the Japanese faced several Sherman tanks. Lacking any sort of anti-tank weaponry, the Japanese troops were unable to damage a single tank, and flowing over and past them, continued on down the draw. Those troops who were unable to reach the draw regrouped and charged another point in the Marine line and fought hand-to-hand until their numbers became depleted.[23]

The 3rd Battalion of the 18th Regiment, led by Major Yukioka Setsuo, was able to exploit a gap between the lines of the 9th and the 21st Marines, and drove hard toward the Marines' regimental Command Post (CP) near the beach. The Japanese came close to overrunning the CP, but Yukioka's attack was blunted by desperate fighting during the Marines' counterattack supported by artillery and mortars. One element of the 3rd Battalion encountered and attacked the 3rd Marine Division Headquarters area. The Japanese were prevented from overrunning the position only when every available Marine, including cooks, clerks, doctors, and some of the wounded, joined the fighting, before two companies of combat engineers arrived to support the defenders. The engineers counterattacked, and by dawn the Japanese troops were dead or scattered;[24] many fled up the Nidual River valley. The Engineers pursued, and over the course of the day reported witnessing many of the Japanese committing suicide by an unprecedented method: when a Japanese soldier had given up on escape, and capture seemed imminent, he pulled the pin of his grenade, placed it on top of his head, then held his helmet down over the grenade and waited for the inevitable.[25]

By the morning of 26 July, it was apparent that the attack to dislodge the American position had failed, as had the breakout attempt at Orote Peninsula.[26] It was also apparent to General Takashina that victory at Guam would be impossible, due to enormous losses in personnel, leadership, weapons, and morale. Takashina decided that all remaining troops should escape to the interior of the island, in order to regroup, and carry on a guerrilla campaign to inflict as much damage as possible on the American forces.[14] During the previous night's fighting, most of the men of the 18th Regiment had been killed in action,[1] along with their commanding officer, Colonel Hikoshiro Ohashi.[27] By the end of 26 July 1944, the 18th Infantry Regiment had ceased to be a functioning unit.[1][2]