The most significant defeat of Confederate forces outside of Gettysburg was at Chickamauga on Sept. 18-20, 1863. It involved the highest number of confederate losses with 18,454 killed, wounded, or captured. Union losses were 16,170 men killed, wounded or captured. Overall, it was the second highest casualty count for both sides apart from Gettysburg. Forces on both sides were nearly equal, with 65,000 Confederate soldiers outnumbering Union soldiers by just 5,000 men. It was also the first engagement in Georgia and even though Confederate losses were significant, the army emerged victorious as a result of a few key maneuvers that allowed them to breach the Union line and eventually force a retreat.