Avro 504

The Avro 504 was a two-seater biplane that first flown on 18th September 1913 and was powered by an 80hp Gnome Lambda rotary engine.
It was basically a development of the previous Avro 500 model. It was designed for training and private flying purposes made entirely out of wood with two bays and a square fuselage.

Some small numbers were bought by both the Royal Flying Corps (RFC) and the Royal Naval Air Service (RNAS) before the start of the World War I and, when it started, they were taken to France. It was the first type of British airplane shot down by the Germans on 22nd August 1914 and also the first type of British airplane to perform an air raid when four 504s from a special unit of the RNAS bombed the Zeppelin works at Friedrichshafen, close to the German-Swiss border.
The airplanes departed from the French city of Belfort on 21st November 1914 each of them carrying four 20lbs (9kg) bombs. One aircraft was shot down but the raid was nonetheless a success as several direct hits destroyed the hydrogen generating plants.

It was also the first airplane of the World War I to perform an strafing attack, when on 22nd October 1914, an airplane manned by Strange and Penn-Gaskell fired their crudely fitted Lewis Mk.I machine gun (which in fact was fitted with the tail-boom of a wrecked Farman biplane and a rope) at a train and enemy troops in the French town of Pérenchies.

Sources:
1. https://en.wikipedia.org/wiki/Avro_504
2. Salamander Books - The Complete Book of Fighters