On March 10, Lincoln promised amnesty to all AWOL soldiers if they returned to active duty by April 1…otherwise they would be arrested for desertion. Then, in a letter to Andrew Johnson, the Tennessee governor who would be his presidential successor, Lincoln suggested enlisting black soldiers. “The colored population,” Lincoln wrote, “is the great available - and yet unavailed of - force for restoring the Union.” Fortunately, the Union heeded Lincoln’s advice…and won the war with a large, powerful army.