Ramadi, Iraq, 2006: Bow gunners on a U.S. Marine patrol boat scan the banks of the Euphrates River for trouble early one morning near Ramadi. The river — an ancient source of sustenance and means of travel for Iraqis in cities and villages — has been used by insurgents to ferry arms from rural areas to the city of Ramadi, on the river’s southern bank. They have also used small islands and sandbars along the waterway to launch mortars and rockets at U.S. positions. Dam Security Unit Two has played a growing role in efforts to capture key cell leaders and interdict mortar and rocket teams who have taken to the river to avoid checkpoints on land.

Read about the Marines’ mission.