Bristol Blenheim

Designed as a light bomber, the Bristol Blenheim was pressed into service, as a fighter, during the Battle of Britain. Early in its trials, it was shown to be too slow to be used as an independent bomber, so, in 1938, the decision was made to reassign it to what might seem converse: as a long-range fighter. While it was near-suicidal to take a Blenheim against agile Me-109s in the Battle of Britain, with the advent of airborne radar, the Blenheim became a competent night fighter, both in air defense and bomber escort roles. It remained, however, slow and undergunned.

With the exception of the De Havilland Mosquito, very few aircraft that were originally designed as bombers were useful as fighters, with the possible exception of use as night interceptors with no threat of escort fighters.

It also was used for long-range anti-shipping strike, but tended to be accident-prone, and was, by 1941, replaced in most roles by the Bristol Beaufighter. The Beaufighter still did not have the combat performance of single-engine fighters, but was superior to the Blenheim. Indeed, twin-engined fighter designs, such as the Me-110 were rarely effective in general combat roles, the chief exception being the U.S. P-38.