President Abraham Lincoln has just announced his preliminary Emancipation Proclamation on Sept. 22, 1862.

This week 150 years ago in the Civil War, a nation divided is just beginning to absorb the blunt message that Lincoln’s war will now be a war against slavery in addition to a fight to reunite North and South.

Lincoln declares that if the rebels do not end their fight and rejoin the Union by Jan. 1, 1862, all slaves in the rebellious states would be deemed “forever free” from that time forward.

His move comes a week after the bloody fighting at Antietam. After the battle, The Associated Press reported on Sept. 20, 1862, that hundreds of Confederate stragglers were captured as Robert E. Lee’s battered Army of Northern Virginia retreated southward from Maryland across the Potomac River. It added: “The Confederate army has succeeded in making its escape from Maryland.”

AP’s account of the fighting in Maryland gives new details of the harrowing ordeal for local residents, many of whom hid in their cellars to escape heavy shelling. AP also reports the Antietam losses for the rebels in dead and wounded “will not come far from 18,000 to 20,000” casualties. Modern-day estimates of the battle have put the overall casualty count at 23,100 dead, missing and wounded.

Elsewhere, Confederates who encroached on Kentucky in the summer of 1862 have skirmished with Union forces. But those engagements are overshadowed by the enormity of the Battle of Antietam. Even so, Union soldiers will eventually force the Confederates in Kentucky to withdraw to Lexington and ultimately leave the state for the most part in October 1862.