In the summer of 1862, after a year of protracted fighting, Abraham Lincoln decided on a radical change of strategy, one that abandoned hope for a compromise peace and committed the nation to all-out war. The centerpiece of that new strategy was the Emancipation Proclamation: an unprecedented use of federal power that would revolutionize Southern society.

Turning point : military stalemate and strategic initiatives : July 1862 -- The Confederate offensive : August 1862 -- The invasion of Maryland : September 2-15, 1862 -- The Battle of Antietam : September 16-18, 1862 -- The revolutionary crisis : September 22-November 7, 1862.