What was a major US Civil War battle that almost gave the Confederates a large troop advantage?

Answer 1

The major US Civil War Battle of Seven Pines or as many call it the Battle of Fair Oaks, saw the Confederate army having an opportunity to engage the Federals with a five to three troop advantage. This chance was a battle within the Union's Peninsula campaign. In late May, 1862, the Army of Northern Virginia was led by General Joseph Johnston. He conceived plans in which he could mass about 50,000 troops against 30,000 Federals near the Chickahominy River. The planned battle by Johnston never came to pass as he wished because confusion and inexperience by the South let the advantage slip away.Johnston's problem was the failure of coordinating three of his generals to follow separate paths and meet a Federal force of 30,000 holding down the crossroads of Seven Pines. Many historians place the blame on Confederate General Longstreet for misinterpreting orders and instead of meeting other Confederate forces, his troops ended up being behind one of the other armies.

If any bone can be thrown to the misfortunes of the South, General Johnston was wounded in the battle that erupted and he had to be replaced by Jeff Davis with Robert E. Lee.