The landing force suffered and bled but did not panic. The profusion of combat veterans throughout the rank and file of each regiment helped the rookies focus on the objective. Communications remained effective. Keen-eyed aerial observers spotted some of the now-exposed gun positions and directed naval gunfire effectively. Carrier planes screeched in low to drop napalm canisters. The heavy Japanese fire would continue to take an awful toll throughout the first day and night, but it would never again be so murderous as that first unholy hour. Marine Sherman tanks played hell getting into action on D-day. Later in the battle these combat vehicles would be the most valuable weapons on the battlefield for the Marines; this day was a nightmare. The assault divisions embarked many of their tanks on board medium landing ships (LSMs), sturdy little craft that could deliver five Shermans at a time. But it was tough disembarking them on Iwo’s steep beaches. The stern anchors could not hold in the loose sand; bow cables run forward to “deadmen” LVTs parted under the strain. On one occasion the lead tank stalled at the top of the ramp, blocking the other vehicles and leaving the LSM at the mercy of the rising surf. Other tanks bogged down or threw tracks in the loose sand. Many of those that made it over the terraces were destroyed by huge horned mines or disabled by deadly accurate 47mm anti-tank fire from Suribachi. Other tankers kept coming. Their relative mobility, armored protection, and 75mm gunfire were most welcome to the infantry scattered among Iwo’s lunar-looking, shell-pocked landscape. [Illustration: _Shore party Marines man steadying lines while others unload combat cargo from boats broached in the surf. Note the jeep, one of the first to come ashore, bogged down axle-deep in the soft black volcanic ash, not to be moved till later._ Department of Defense Photo (USMC) 110593 ] Both division commanders committed their reserves early. General Rockey called in the 26th Marines shortly after noon. General Cates ordered two battalions of the 24th Marines to land at 1400; the 3d Battalion, 24th Marines, followed several hours later. Many of the reserve battalions suffered heavier casualties crossing the beach than the assault units, a result of Kuribayashi’s punishing bombardment from all points on the island.