In order for bombers to conduct skip or mast-height bombing, the target ship's antiaircraft artillery would first have to be neutralized by strafing runs. For the latter task, Major Paul I. "Pappy" Gunn and his men at the 81st Depot Repair Squadron in Townsville, Queensland, modified some USAAF Douglas A-20 Havoc light bombers by installing four machine guns in their noses in September 1942. Two fuel tanks were added, giving the aircraft more range. An attempt was then made in December 1942 to create a longer range attack aircraft by doing the same thing to a B-25 medium bomber to convert it to a "commerce destroyer", but this proved to be somewhat more difficult. The resulting aircraft was nose-heavy despite added lead ballast in the tail, and the vibrations caused by firing the machine guns were enough to make rivets pop out of the skin of the aircraft. The tail guns and belly turrets were removed, the latter being of little use if the aircraft was flying low. The new tactic of having the B-25 strafe ships would be tried in this battle.