Why did the Canberra carry no defensive armament?

Short answer

Because the requirement demanded it: the Air Ministry's 1944 specification to succeed the Mosquito, in its initial E.3/45 revision, called for a fast, high-altitude bomber with no defensive armament. That armament had historically proven unable to match fighters, and the resulting performance gain let the Canberra avoid air-to-air combat.

Published: November 4, 2026 · Updated: November 4, 2026 · Edited by Above Ten Thousand · Editorial policy

Why did the Canberra carry no defensive armament?

1 LRF RAAF Canberra bomber aircrew

A 1944 requirement

The Canberra formally originated from a requirement issued in 1944 by the Air Ministry to replace the de Havilland Mosquito; that specification, in its initial E.3/45 revision, called for a high-altitude, high-speed bomber that was not to be fitted with defensive armament.

Performance instead of turrets

Also following the Mosquito's philosophy, the Canberra was designed without defensive armament, which had historically proven unable to match fighters, and the resulting performance gain let it avoid air-to-air combat entirely. The first of the prototypes, VN799, made its maiden flight on 13 May 1949. In May 1951 the Canberra entered squadron service with the RAF.

Altitude and production

On 4 May 1953, the Canberra B.2 WD952, fitted with Rolls-Royce Olympus engines, set a world altitude record flying at 63,668 ft (19,406 m). On 28 August 1957, the Canberra B.2 WK163, fitted with a Napier Double Scorpion rocket motor, achieved an altitude record of 70,310 ft (21,430 m). A total of 901 Canberras were built across the various British manufacturers, and together with overseas licence production the worldwide total reached 1,352 aircraft. The USAF decided to order 403, built under licence by the Glenn L. Martin Company as the B-57 Canberra. The Government Aircraft Factories locally assembled 48 for the Royal Australian Air Force.