[Illustration: _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]
[Illustration: _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]