Union forces looked up the North Anna River from the south bank at Jericho Mills, Virginia, on May 24, 1864, observing a canvas pontoon bridge and a pontoon train waiting on the opposite bank. The fascinating engineering layer to this Civil War photograph is the hidden ingenuity of the canvas boats visible in the water. Unlike traditional, heavy wooden pontoon boats that required massive teams of horses to transport, these innovative canvas models consisted of lightweight wooden frames wrapped in heavy, waterproofed canvas sheets. This allowed the Union army to pack an entire bridge onto a few light wagons, rapidly assemble the structures at the riverbank, and cross treacherous waters like the North Anna River before the Confederate forces could organize a defense.