the capital, lincoln once again calls on george mcclellan. >> lincoln's decision to replace mcclellan with johnmcclellan... >> present arms! >> ...the devil you know, back in charge, in spite of all that's happened before. >> the president has made his decision. stand by me and all will be well. >> hoping to end the war swiftly, lee marches his army across the potomac into maryland, carrying the fight to union soil for the first time. with his invasion of maryland, lee is hoping to get the fighting out of northern virginia. [ reel ticking, shutter clicks ] the bigger picture that he's after is this one decisive battle on northern soil that, in this case, might drive maryland into the confederacy. ♪ >> when the rebels invade maryland, lee sees himself as a liberator, freeing the state from an oppressive federal government. now, southerners view lincoln as a tyrant for imposing martial law in response to the baltimore riot, and are convinced that maryland will secede once the confederates arrive. but the truth is, as a border state, maryland's loyalties are still divided. and when lee's troops oc