A U.S. Navy gun crew mans a 20mm Oerlikon anti-aircraft mount aboard ship somewhere in the Pacific during World War II. Stripped down against the tropical heat, with only one man donning a steel helmet, the sailors exemplify the informal, ready-at-all-times posture of shipboard gun crews who stood constant watch against the threat of enemy air attack. The Oerlikon, adopted widely by the U.S. Navy from 1942 onward, became the backbone of close-in anti-aircraft defense for vessels of all sizes across the Pacific campaign. Project: 218696