The PB4Y-1 was a navalized version of the B-24 Liberator. The fisrt PB4Y-1s were essentially the same as the B-24D but later Navy Liberators were based on the later B-24G, J, L and M variants, many being fitted with ERCO nose ball turrets instead of the Consolidated A-6A/B or Emerson nose turrets. The type flew long-range anti-submarine patrols over both the Atlantic and Pacific Oceans and is credited with 13 U-Boats sunk.