Who won the first battle at bull run and what did this battle prove?

1.
The Confederates won

2. 
The First Battle of Bull Run (called First Manassas in the South) cost some 3,000 Union casualties, compared with 1,750 for the Confederates. Its outcome sent northerners who had expected a quick, decisive victory reeling, and gave rejoicing southerners a false hope that they themselves could pull off a swift victory. In fact, both sides would soon have to face the reality of a long, grueling conflict that would take an unimaginable toll on the country and its people.

Dpolitical is the answer