Based on the Lockheed Model 18 and last in the long line of descendants of the L.10 (which included the A-28/29 Hudson), the PV series of patrol bombers were very effective aircraft which served with US and British forces from the mid-war period onwards. Similar in appearance to the Hudson, the initial design was the PV-1 Ventura patrol bomber, built originally for the RAF as a day-bomber but which eventually entered service with the US and other Commonwealth nations such as Australia, Canada, New Zealand, and South Africa). Later, the basic airframe was redesigned into the PV-2 Harpoon. With an internal bomb bay and external hard-points, the Harpoon could carry bombs, depth charges, mines, rockets, as well as external fuel tanks giving them the ability to make bombing and rocket attacks all over the Pacific, including the Japanese home islands. Over 3,000 Venturas and Harpoons were eventually built by Lockheed and served in various non-combat duties worldwide for decades to come.

Built to a British requirement for a Hudson replacement, the first Ventura Mk. I flew on 31 July 1941 and entered service slightly less than a year later. It was followed by the Mk. II and the lend-lease supplied Mk. IIA both of which featured uprated engines. They were employed mainly as RAF day-bombers but were only marginally successful. Later they were used by Coastal Command as the GR.I and GR.V a role for which they were more properly suited. In USN and USMC service, Venturas were built as the PV-1 with a solid nose and the PV-3 which were basically requisitioned Mk. IIs. A photo-recon version was the PV-1P and some basic models were equipped with British AI radar for night fighter duties. The USAAF was also a user of this aircraft, naming them B-34 and B-37 the latter with a different engine set. Its main successor in the late-war period was the PV-2 Harpoon which retained the powerplant of the Ventura but had a larger structure, increased fuel capacity and bomb load as well as improved armament. The only major subvariant was the PV-2D which had three additional fixed guns in the nose for ground attack.