The bomber was also used by the United States Army Air Forces (USAAF), which designated it the Lockheed B-34 (Lexington) and B-37 as a trainer.

Used in daylight attacks against occupied Europe, they proved to have weaknesses and were removed from bomber duty and some used for patrols by Coastal Command.

After USAAF monopolization of land-based bombers was removed, the US Navy ordered a revised design which entered service as the PV-2 Harpoon for anti-submarine work.

At the start of the war, Lockheed proposed military conversions of the Lodestar for the RAF as replacement for the Hudson reconnaissance aircraft and the Bristol Blenheim bomber.

Lockheed needed more production capacity and nearby Vega Aircraft Corporation was contracted for building the Ventura.

Venturas were initially used for daylight raids on occupied Europe but, like some other RAF bombers, they proved too vulnerable without fighter escort, which was difficult to provide for long-range missions.

Before completion of the first O-56, the U.S. Army Air Forces dropped the "O-" category used to designate "observation" (reconnaissance) aircraft.

Late production PV-1s dispensed with this bombardier position and replaced it with a pack with three 0.50 inch (12.7 mm) machine guns underneath the nose.

Some other significant developments included the increase of the bombload by 30% to 4,000 lb (1,800 kg), and the ability to carry eight 5-inch (127 mm) HVAR rockets under the wings.

Ex-military PV-1 Venturas from Canada and South Africa were converted by Howard Aero in San Antonio, Texas, in the 1950s and 1960s as high-speed executive transports.

The earliest conversions, called Super Venturas, incorporated a 48 in (122 cm) fuselage stretch, extra fuel tankage, large picture windows, luxury interiors, and weapons bays transformed into baggage compartments.

[4] A final PV-1 modification by Howard was the Eldorado 700, with longer wings, a pointed nose, and streamlined engine cowlings.

The company plane was bound for Winnipeg, Manitoba, but had trouble with both engines and crashed shortly after takeoff from Mitchell Field in Milwaukee, Wisconsin.

[10] The Portuguese Air Force received 42 Lockheed PV-2C Harpoons from 1953, which replaced the Curtiss SB2C-5 Helldiver as an anti-submarine aircraft.

They served mainly as light bombers and ground attack aircraft, with occasional reconnaissance, transport and maritime patrol sorties.

The first Ventura Mark Is were accepted by the Royal Air Force (RAF) in September 1941, with aircraft being delivered to Britain from April 1942.

[15][16] On 6 December 1942, 47 Venturas from 21, 464 (RAAF) and 487 (RNZAF) squadrons participated in Operation Oyster, the large daylight 2 Group raid against the Philips radio and vacuum tube factories at Eindhoven.

Squadron Leader Leonard Trent (later the last of the Great Escapers) won the Victoria Cross for his leadership in this raid.

459 Squadron RAAF was equipped with the Ventura V between December 1943 to July 1944, flying mainly anti-submarine and anti-shipping patrols.

Vs were used operationally by the RCAF from 16 June 1942 to 18 April 1947 in the home defence coastal patrol role in both Eastern and Western Air Command.

IIs were used in a training role at 1 Central Flying School, Trenton, Ontario, and at RCAF Station Pennfield Ridge, New Brunswick (RAF No.

In December 1942 four SAAF Venturas dropped supplies to survivors of the Dunedin Star shipwreck on South-West Africa's Skeleton Coast.

Despite that the RNZAF Venturas came to be among the most widely used of any nation's, seeing substantial action until VJ Day over South West Pacific islands.

RNZAF machines often clashed with Japanese fighters, notably during an air-sea rescue patrol on Christmas Eve 1943.

By late 1944 the Ventura began to be phased out of frontline action as the RNZAF backed away from the Patrol Bomber concept, orders for PV-2 Harpoons were canceled after a handful of aircraft had been delivered.

[citation needed] During the early months of 1942, the primary responsibility for anti-submarine warfare in the United States was shouldered by the Army Air Forces.

To carry out such a task, the Navy was pursuing a long-range, land-based patrol and reconnaissance aircraft with a substantial bomb load.

In exchange for use of the Renton plant, the Army Air Forces would discontinue its objections to Naval land-based bombers, and provide aircraft to the Navy.

One of the clauses of this agreement stated that production of the B-34 and B-37 by Lockheed would cease, and instead these resources would be directed at building a navalized version, the PV-1 Ventura.

After the war, the U.S. Navy deemed many PV-1s obsolete and the aircraft were sent to Naval Air Station Clinton, Oklahoma to be demilitarized and reduced to scrap.