Breguet Bre.4

Bre.4
A Breguet BUC/BLC de Chasse operating with No. 5 Wing, Royal Naval Air Service, in Belgium sometime between April and June 1916
Role	Bomber
Manufacturer	Breguet, Michelin
Designer	Louis Charles Breguet
First flight	1914
Introduction	1914
Primary users	French Army Royal Naval Air Service
Number built	ca. 100

This article is about an aircraft of World War I. For the pre-war design of the same designation, see Breguet Type IV.

The Breguet Bre.4, also known variously as the Type IV and BUM, was a French biplane bomber of World War I. A fighter version of it was also produced as the BUC and BLC; some of these saw service with the British Royal Navy, which called them 'the Breguet 'de Chasse.

The Bre.4 was developed during 1914 when French military planners began to express a preference for pusher- over tractor-configured aircraft, leading Breguet Aviation to cease further development of its original Type IV design and pursue military contracts with an aircraft of the preferred layout. The Type IV was a two-bay, equal-span, unstaggered biplane that seated the pilot and observer in tandem open cockpits in a nacelle that also carried the pusher engine at its rear, and the tricycle undercarriage.

As the prototype neared completion, the Breguet factory at Douai was threatened by the advancing German Army, and the machine and its builders were evacuated to Villacoublay where construction and testing were completed. At this point, André and Édouard Michelin approached the French government with an offer to sponsor the construction of 100 bombers for the French Army, and were awarded a licence for the Breguet design. This was put into production as the BUM (B for pusher-driven, U for Canton-Unné-powered, M for Michelin). A later revised bersion, the BLM, was the definitive Renault-powered version.

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