Biak Island, off the northwest coast of New Guinea, was the next step in MacArthur’s relentless march towards the Philippines. The island’s airfields blocked access to Geelvink Bay, which was required to continue the advance across New Guinea. Furthermore, the capture of Biak would put all of northwest New Guinea in range of Allied airpower. The Japanese knew this and planned on holding the island at all costs. The Japanese commander on the island, Col Kuzume Naoyuki, developed new tactics based on the experiences of previous battles. He knew the Americans would expect a Tarawa-like defense of the beach and plan for it. Therefore he had his troops defend inland, and ambush the unsuspecting Americans and Australians on their way to the obvious objective on the island: the three large airfields.
On 27 May 1944, the US 41st Infantry Division, consisting of National Guardsmen from the Pacific Northwest, had an unopposed landing after a furious bombardment by the US Navy. They naively assumed the bombardment destroyed any Japanese, and confidently headed inland. They walked right into Kuzume’s elaborate ambushes in depth consisting of pillboxes, honeycombed into the hills, supported by platoon strongpoints, forward supply depots in caves, minefields, pre-sited artillery and mortars, and tank counterattacks. The Guardsmen were initilly tore apart. The remains of the lead battalion could only be extracted from the kill zone by amtraks and tanks, and then only at night.
The “Sunsetters” were veterans of the two year long march across New Guinea, but this was the worst action they had seen. Every Japanese position had to be taken by close combat, and every Japanese position was inside the kill zone of a supporting position. Kuzume’s “cave defense” slowed the Allied advance across the island to a crawl. Even worse for the attackers, he forced his troops to abandon the suicidally wasteful banzai charges brought about by a perverted Bushido code that saw cowardice in any withdrawal. Kuzume made the Sunsetters pay for every yard they gained as his men slowly fell back from prepared fighting position to prepared fighting position all the way to the western end of the island.
It took the entire division until August to secure Biak using flamethrowers, satchel charges and bayonets. It would then take six more months to reinforce, rebuild, retrain, and refit the division.
Kusume’s defense was a taste of what was to come. His effective reforms became the standard Japanese island defensive tactics for the rest of the war. The Japanese fought for Saipan, Tinian, Guam, Anguar, Peleliu, the Philippines, Iwo Jima, and Okinawa using Kusume’s methods and techniques.