The Royal Hibernian Military School was founded in Dublin, Ireland, to educate orphaned children of members of the British armed forces in Ireland.
The foundation of the School came about in 1769 when King George III granted a Charter of Incorporation on 15 July, the School Governors holding their inaugural meeting on 6 November in Dublin Castle.
T he buildings housing the school were erected in the Phoenix Park, overlooking the village of Chapelizod in the Liffey valley (in full view of Wicklow mountains). It first took in 90 boys and 50 girls as pupils (in the charge of an Inspector and Inspectress, assisted by the Chaplain and an assistant mistress) in March 1770. The site originally occupied 3 acres (12,000 m2) but by 1922 its boundary walls enclosed thirty three acres.
By 1808 the system and organisation of the school followed closely that of its sister school, the Duke of York's Royal Military School (then at Chelsea, London, England). By 1816, when Thomas Le Fanu (father of Sheridan Le Fanu) took over as chaplain, there were 600 children at the school.
In 1853 the school's first "stand of colours" were presented by the then Prince of Wales and, in the same year, the girls at the school left to join their own separate establishment, the Drummond School, which was founded for them at Chapelizod.
In 1922 the Royal Hibernian Military School moved to Shorncliffe, in Folkestone, Kent and in 1924 it was merged with the Duke of York's Royal Military School which last, by then, was in its current location atop 'Lone Tree Hill' above Dover Castle.