Underway Replenishment at Sea. A U.S. Navy guided missile escort, hull number 15, steams close alongside during an underway replenishment (UNREP), the routine but demanding maneuver by which warships transferred fuel, ammunition, and supplies without breaking formation. Photographed from the deck of an aircraft carrier operating in the Pacific during the Vietnam War, this image captures the coordinated seamanship required to keep two vessels running on parallel courses just yards apart while lines and hoses passed between them, sustaining round-the-clock combat air operations far from any port. Project: 218408