The Battle of Bull Run, which was the first major battle of the American Civil War, showed both sides the brutal and bloody reality of war. For the Confederates, it demonstrated that they were capable of defeating Union forces and gave them confidence in their military prowess. For the Union, it showed that the war would be much more difficult and costly than initially anticipated, as their forces suffered heavy casualties and were ultimately defeated. Overall, the Battle of Bull Run underscored the seriousness and gravity of the conflict that both sides were engaged in.
