What 2 factor led to a southern victory at the second battle of bull run?

The Second Battle of Bull Run (Manassas) proved to be the deciding battle in the Civil War campaign waged between Union and Confederate armies in northern Virginia in 1862. As a large Union force commanded by John Pope waited for George McClellan’s Army of the Potomac in anticipation of a combined offensive, Confederate General Robert E. Lee decided to strike first. Lee sent half of his Army of Northern Virginia to hit the Federal supply base at Manassas.