Confederate General P.G.T. Beauregard, who was using McLeanâs house as his headquarters, wrote: â⦠of this artillery fight was the destruction of the dinner of myself and staff by a federal shell that fell into the fire-place of my headquarters at the McLean House.â The Confederates won the First Battle of Bull Run due in large part to General âStonewallâ Jackson holding his ground like a âstonewall,â resulting in his nickname. With momentum on their side, Confederate troops could have pursued the fleeing and exhausted Union army 20 miles into Washington and promptly won the war. Instead, a heavy downpour of rain turned roads into mud pits and the pursuit was called off.