Complex sentence: The opposing gangs'outfits were based on the uniforms of the American Civil War, with the 245's outfits representing the uniforms of the Confederate Army and the 248's outfits representing the uniforms of the Union Army.
Split into simpler sentences: The opposing gangs'outfits were based on the uniforms of the American Civil War. The 245's outfits represented the uniforms of the Confederate Army, and the 248's outfits represented the uniforms of the Union Army.