The Battle of Manassas (also known as the second Battle of Bull Run) was an unsuccessful Union assault on a small force of Confederate troops under Jackson on August the 29th 1862 during the American Civil War. General Pope, commanding 40,000 men advanced to attack the Confederate force led by Jackson, who was awaiting reinforcements from Robert E Lee at Bristoe station. Jackson retired to Manassas Junction and took a strong defensive position near Gainesville behind an old railway grading. Pope ordered Sigel to attack during daylight on August the 29th, and all morning a duel of batteries continued that by noon had resulted in heavy casualties on both sides. The battle continued until darkness, was suspended overnight and continued early the next morning but the Union forces were too tired and were forced to withdraw. Research Battle of Manassas