The Union troops are having a hard time holding their position and trying not to have their camps overrun.
The Rebels are making a good charge into Union troops already softened up by Confederate artillery. Several Union units have already routed over the bridge and heading away as fast as possible.
The Rebel yell can be heard through the wheat field and beyond. Note: you can see several different techniques and materials that I use for fields. (Lower left: Carpet sample. Lower right, Green corn: grass/floor/welcome mat. Center, Rows of dirt: Icky Brown Corduroy material covered with glue and tan flocking on the 'ridges'. Back, Center: Wheat field from another grass/welcome mat.)