The Drive North
The landing force still had much to learn about its opponent. Senior intelligence officers did not realize until 27 February, the ninth day of the battle, that General Kuribayashi was in fact on Iwo Jima, or that his fighters actually numbered half again the original estimate of 13,000.
For Kuribayashi, the unexpectedly early loss of the Suribachi garrison represented a setback, yet he occupied a position of great strength. He still had the equivalent of eight infantry battalions, a tank regiment, two artillery and three heavy mortar battalions, plus the 5,000 gunners and naval infantry under his counterpart, Rear Admiral Toshinosuke Ichimaru. Unlike other besieged garrisons in the Central Pacific, the two Japanese services on Iwo Jima functioned well together.
Marine Corps Historical Collection
Marine half-track scores a hit on a Japanese strongpoint with its 75mm gun.
Kuribayashi was particularly pleased with the quality of his artillery and engineering troops. Colonel Chosaku Kaido served as Chief of Artillery from his seemingly impregnable concrete blockhouse on a promontory on the east central sector of the Motoyama Plateau, a lethal landmark the Marines soon dubbed “Turkey Knob.” Major General Sadasue Senda, a former artillery officer with combat experience in China and Manchuria, commanded the 2d Independent Mixed Brigade, whose main units would soon be locked into a 25-day death struggle with the 4th Marine Division. Kuribayashi knew that the 204th Naval Construction Battalion had built some of the most daunting defensive systems on the island in that sector. One cave had a tunnel 800 feet long with 14 separate exits; it was one of hundreds designed to be defended in depth.
The Japanese defenders waiting for the advance of the V Amphibious Corps were well armed and confident. Occasionally Kuribayashi authorized company-sized spoiling attacks to recapture lost terrain or disrupt enemy assault preparations. These were not suicidal or sacrificial. Most were preceded by stinging artillery and mortar fires and aimed at limited objectives. Kuribayashi’s iron will kept his troops from large-scale, wasteful Banzai attacks until the last days. One exception occurred the night of 8 March when General Senda grew so frustrated at the tightening noose being applied by the 4th Marine Division that he led 800 of his surviving troops in a ferocious counterattack. Finally given a multitude of open targets, the Marines cut them down in a lingering melee.
For the first week of the drive north, the Japanese on Iwo Jima actually had the attacking Marines outgunned. Japanese 150mm howitzers and 120mm mortars were superior to most of the weapons of the landing force. The Marines found the enemy direct fire weapons to be equally deadly, especially the dual-purpose antiaircraft guns and the 47mm tank guns, buried and camouflaged up to their turrets. “The Japs could snipe with those big guns,” said retired Lieutenant General Donn J. Robertson. The defenders also had the advantage of knowing the ground.