A U.S. Army CH-47 Chinook helicopter flies low above the water's surface of the Arkansas River to drop off a team of divers during Operation River Assault at Fort Chaffee, Ark., July 24, 2013. Bridge-building units with the 671st Engineer Company (Multi-Role Bridge), of Clackamas, Ore.; 459th Engineer Company (MRB), of Bridgeport, W.Va.; and 74th Engineer Company (MRB), of Fort Hood, Texas, worked together to assemble a floating bridge and provide support during the exercise. (U.S. Army photo by Sgt. 1st Class Michel Sauret/Released)