The heaviest losses the 140th New York would incur in a single battle were incurred during severe fighting in the Battle of the Wilderness between May 5–7, 1864. The 529 soldiers of the 140th NY led the opening of the battle with a charge across Saunders Field, and were among the first Union troops to engage the Confederacy in battle. The 140th took unsupported flank fire for over 30 minutes and sustained 255 total casualties. Estimates of exact losses are 50 enlisted men, and 3 officers killed in action or died of wounds sustained during battle. A further 98 enlisted and 3 officers injured. 101 total personnel were reported missing or captured. Captain Willard Abbott was counted among the wounded.