In 1778, parliamentary legislation  allowed Catholics to join the British army for the first time since the 17the century, as additional troops were needed to serve in the American Revolutionary War. Throughout most of the 19th century, Irish were the largest minority ethnic group in the British Imperial Army. It is estimated that they formed approximately 40% of the military when World War One broke out in 1914. However it was a membership divided along class and religious lines- the Catholic peasantry served as infantry whilst officers came from the Protestant Anglo-Irish landed establishment. Each joined for very different reasons- the Catholics largely to escape extreme poverty, the gentry to continue the millennia old tradition of serving as mounted warriors or knights of an elite fighting force. An’ Officer’ and a ‘Gentleman’ were interlinked. The British Army, as with most contemporary imperial armies, was a very racist, sectarian and class-based hierarchical organisation.

World War One changed all that. Irish nationalists in large numbers answered the call of John Redmond, leader of the Irish Parliamentary, Party to help liberate Catholic Belgium from German occupation and to secure Home Rule for Ireland. They joined not only the traditional upper middle class and land-owning gentry but also the Protestant working class and farmers primarily from Ulster who wanted to prove their loyalty to the British crown and to ensure that Home Rule for Ireland never happened.  Furthermore, the high casualties amongst junior officers in the first year of the war forced the army to look for candidates for commissions from lower social classes and certain religions that previously would have been considered unsuitable.

Over 200,000 men from Ireland fought during the Great War, in all branches of the British armed forces, namely the army, navy and air force(corp). 49,400 Irish died in the conflict.