"Once the Marianas were taken B-29s needed an emergency field and a forward base for fighter escort. Iwo Jima was chosen for V Amphibious Corps to assault on 19 February 1945. The assault had 4 battalions tasked as shore party: 4th & 5th Pioneers and 31st & 133rd CBs. The 133rd suffered the most casualties in Seabee History tasked to the 23rd Marines D-day-D+18. Only basic road construction was accomplished during the first days. Work on the first airfield began on D+5. On Iwo Jima it got so that the Marines would hold up the assault to wait for one of their Seabee built flamethrowering tanks.