The tragedy, from the southern viewpoint, is that a couple of huge Confederate victories had already occurred at Fredricksburg and Chancellorsville which illustrated the correct strategy and tactics. Sit back in defensible positions and let the Union attack head on, or launch surprise attacks, in their own territory where they knew the terrain, all the while constantly attacking Union supply lines. In other words, use the advantages of defense.
We would be using Confederate currency today had Lee listened to Longstreet at Gettysburg. Lee broke his own, and a well-proven rule of warefare: choose the ground where you fight. Stuart left him blind.
I recall that after First Manassas, Southrons could have marched on Washington with little resistance. I think the armies were still feeling each other out; you know what they say about hindsight. Of course Mclellan had many more opportunities to capture the ANV, but never pulled the trigger.