Although the Japanese suffered a devastating loss at Saipan, the Imperial Japanese General Staff considered the battle lost by the Japanese Navy, not the Japanese Army: the Americans took enormous casualties taking the island. The battle validated the new Japanese island defensive tactics of dug in ambushes, interlocking fields of fire, infiltration and night counterattacks instead of defending on the beaches. The Imperial General Staff planned for the new doctrine to buy the Japanese Navy the time necessary to create the opportunity for the Khitai Kessen, or the decisive battle that would end the war. Furthermore, the war in the Pacific would become an attritional battle and the casualties sustained in taking each island could break the will of the American people.
Lt Gen Sadae Inoue, commander of the 14th Infantry Division was charged with the defense of the Palau Islands, which were tailor made for the new defensive tactics. The three islands of Peleliu, Ngesebus, and Angaur consisted of steep ridges honeycombed with caves that were perfect for this defense. His 14000 troops had four months to prepare for an American invasion. He dug his artillery in deep and his troops prepared to fight from underground for the entire battle. One of Inoue’s regimental commanders, Kunio Nakagawa, would not slavishly follow the new doctrine though. On Peleliu, the only landing areas were small and obvious and they were covered by a small outcropping on the southern coast (The Point) that enfiladed the entire beach, which could only be assaulted from inland. On Peleliu, Nakagawa planned for the Americans to fight a Tarawa style battle at the beach, followed by a Biak and Saipan style battle further inland. And the the Marines did.
On 15 September 1944, the US 1st Marine Division landed on the island of Peleliu in order to secure MacArthur’s right flank from attack as he returned to the Philippines and secure the Palau’s airfields for future use. The US Navy’s three day bombardment had little effect on Inoue’s defenses. The Marines took enormous casualties seizing the beachhead, the airfield, and finally the Point. The Japanese counterattacked with 13 Type 95 Ha Go tanks and 200 infantry supported by artillery and mortars, and nearly retook the airfield. Japanese artillery fire from Ngesebue Island and Umurbrogol Mountain, soon to be nicknamed Bloody Nose Ridge, made every square foot of Peleliu unsafe.
On 19 Sep, the Marines began their assault on Bloody Nose Ridge. The Marines quickly found that grenades and flamethrowers were no longer sufficient to root the Japanese out of their caves because they were too deep. Every cave had to be cleared and sealed, and the Japanese were ingenious in concealing entrances and firing holes. In the next six days Chesty Puller’s 1st Marine Regiment took 70% casualties. On 20 September, the 5th Marines invaded Ngesbue Island to silence the artillery there that was devastating the troops on Peleliu.
Marine regiments, and soon US Army regiments from the 81st US “Wildcats” Infantry Division were rotated through the fight for the ridge. On 23 Sep, the 7th Marines, and the III Amphibious Corps reserve, the 321st Regimental Combat Team of the US 81st Infantry Division surrounded the mountain and continued the assault. They in turn were replaced by the 5th Marines and the 323rd RCT in early October. The 81st Infantry Division took over the battle on 15 October, after the 1st Marine Division was “fought out”, until the island was declared “secure” on 27 November, two and half months after the initial landing.
The last Japanese unit on the small island didn’t surrender until April… of 1947, and the last Japanese soldier on Peleliu wouldn’t surrender until 1955.
The 1st Marine Division took 7000 casualties, and the 81st took 2500 casualties taking Peleliu. The battle for the Palau’s was the most casualties in one operation in the entire Pacific theatre up to that time. The Imperial Japanese General Staff was correct though: a great controversy immediately arose as to whether the cost to take Peleliu was worth its contribution to MacArthur’s upcoming campaign in the Philippines.