Marines of Battery I, 14th Defense Battalion, man their twin-barrelled, Mark IV, Oerlikon-designed 20mm guns on top of Chonito Ridge, overlooking Adelup Point. In the initial stages of the Guam operation, these antiaircraft guns fired in support of the 3d Marines. Department of Defense Photo (USMC) 93063
A threatening 75mm Japanese gun pokes its barrel out of the Gaan Point pillbox where a companion piece and a 37mm gun wreaked havoc on the assault waves of the 22d Marines on W-Day, destroying approximately 24 troop-carrying amphibian tractors, before the enemy position was taken out. Department of Defense Photo (USN) 247618
