One can argue the point because there were events such as the capture of Camp Jackson in St. Louis, as well as the engagement at Big Bethel, on the Yorktown Peninsula, both of which came earlier. But in terms of a true battle, pitting true armies, Bull Run was certainly the first battle of the war.

Bull Run was also emblematic of the war in many respects. Men on the ground knew little, and their commanders knew only a little more. Smoke obscured parts of the battlefield, and it was nearly impossible for a commanding general to learn all that was happening. Much depended on guesswork, timing, and luck.