Answer:
Perhaps one of the most influential events was when commanding general Benjamin Butler, of Ft. Monroe, a northern stronghold in Virginia, declared escaped slaves to be "contraband" of war. General Butler also refused to recognize Virginia law requiring escaped slaves be returned to their owners. Butlers logic was simple, since Virginia had seceded from the Union, their laws had no jurisdiction. This led to many slaves escaping to the protection of Ft. Monroe which became known as "Freedom Fortress". It also placed slavery squarely in the middle of the politics of the Civil War.