If memory serves me correctly, the strength of the Union army was with Meade in the hills at Gettysburg. There were no quality union forces between Lee and the Capitol including those manning the forts...green recruits, etc. Most would probably have run like hell as they did at Bull Run.
"Most would probably have run like hell as they did at Bull Run."
Bull Run? Where's that?
Ohhh...you mean the Battle of Manassas Junction!