The Lockheed A-28 Hudson was the result of a request that the Lockheed 14 Super Electra airliner be turned into a maritime reconnaissance aircraft. It was first supplied to the British around mid-1939 which used it for North Sea patrols but once the US had entered the war some Lend-Lease Hudsons were repossessed as the A-29 by the USAAF. Among the many milestones of the Hudson, it was the first Allied aircraft to shoot down a German warplane over Jutland, it was involved in the tracking of the German prison ship Altmark in 1940, it was a RAF Hudson from No. 269 Squadron which forced the surrender of U-570 on 27 August 1941 and it was also the first aircraft to sink a U-boat using rockets. Later Hudsons had increased range which permitted them to undertake Atlantic operations, other users included Australia, Canada, the Netherlands, New Zealand, and South Africa. Perhaps more importantly, it was the plane which would put Lockheed at the forefront of military aircraft development.

The first Hudson prototype was flown on 10 December 1938. Given the designation A-28 by the US, the initial batch supplied to the UK were designated Hudson Mk. I by the RAF. Improved propellers were featured in the Mk. II while the Mk. III had a more powerful G-205A engine whereas repossessed US aircraft were designated A-29 but were otherwise no different from the A-28. The final wartime variants were the Mk. IV, V and VI which had more powerful Pratt & Whitney radials as well as different propellers and equipment. USAAF designations for the Hudson corresponded as follows: A-28 (Mk. IV), A-28A (Mk. V), A-29 (Mk. IIIA) and A-29A (Commonwealth variants) while USN versions of the A-29 were known as the PBO-1.