The United States Navy fielded the ASM-N-2 Bat in April 1945 as the first automated anti-ship weapon employed in combat. This radar-guided glide bomb succeeded earlier television and semi-active radar designs that proved inaccurate or less flexible. Development involved the National Bureau of Standards, MIT, Bell Telephone Laboratories and Navy ordnance offices, yielding 72 units by late March for Pacific training.

Squadrons flying PB4Y Privateers launched the first Bats on April 23 against Balikpapan harbor, scoring hits on a freighter, picket boat and oil refinery despite radar confusion from land and mechanical failures from tropical conditions. Later missions from Okinawa produced additional strikes on Japanese vessels until the final combat drop on August 10.