Following his tactical success in the Battle of Second Manassas (Second Bull Run, August 28–30, 1862), Robert E. Lee led his Army of Northern Virginia into western Maryland to secure supplies and recruits—and in the vain hope of winning its people to the Confederate cause. His Special Order No. 191, popularly known as “Lee’s Lost Order,” was discovered by Union troops at an abandoned Confederate campsite near Frederick and turned over to McClellan. Armed with the knowledge that Lee had divided his forces, McClellan realized he could destroy Lee’s army piece by piece. However, once again McClellan’s overly cautious nature proved his undoing, giving Lee enough time to reconcentrate his forces.