7½-TON PONTON BRIDGE OVER THE CHATTAHOOCHEE RIVER near
Ft. Benning, Ga., July 1939.
From the United States Army in World War II-Technical Services- Engineers- Troops and Equipment
Other than the relatively modern field piece (Craig? a 75mm?), the scene above could have been taken from Grants Army of the Potomac in 1865. The ponton bridge in use was a direct descendent of the types of assault bridges in use in the Civil War. At the time the picture was taken, this was the standard assault bridge in the Army. Great efforts were being expended to develop similar ponton bridges with capacities of up to 30 tons to support the armor the Army would use in the war. Primarily, larger pontons (the boat thingies) would be used. Later, pneumatic floats, similar to rubber rafts, would be used to float assault bridges.
Similar floating bridges would remain in use throughout World War II and well into the post-war era until the US adopted the floating ribbon bridge, itself almost a direct copy of a Soviet design.