[1] Hoare entered the Royal Military College, Sandhurst, as a cadet,[1] and after passing out was assigned to the Worcestershire Regiment with the rank of second lieutenant on 8 May 1901.
7 Squadron was then assigned to patrol the front lines between La Bassée and Lens, to provide cover for artillery observation aircraft during the battle of Loos.
The squadron's awards list was opened on 15 July 1915 when Captain John Aidan Liddell won the Victoria Cross, bringing back his damaged aircraft despite being severely wounded.
The squadron also had some success as a bomber unit, notably on a raid in September 1915 when Lieutenant M. G. Christie dropped two 112-pound (51 kg) bombs on the railway yard at Valenciennes from a height of 4,800 feet (1,500 m).
[16] On 13 November 1916 Hoare was one of a long list of officers mentioned in despatches by General Sir Douglas Haig, Commander-in-Chief of the British Armies in France.
[17] In January 1917, Hoare was appointed Officer Commanding, Royal Flying Corps Canada,[18] an organisation formed to recruit and train pilots and aircrew, with its main base at Camp Borden, near Barrie, Ontario.