Dublin Castle Hospital was a product of the First World War. In December 1914, as more and more wounded soldiers arrived in Dublin from the front, a proposal emerged to augment the available medical facilities by converting the ceremonial apartments at the Castle (including the Throne Room) into a hospital. A committee was established, funds were raised, and the Board of Works carried out the necessary conversion works. Royal Army Medical Corps doctors, around sixty nurses, and Red Cross personnel staffed the hospital.
In 1916, the casualties that accumulated during the Rising were cared for at a range of military and civilian hospitals across city, including the hospital at Dublin Castle. During the week of the Rising 176 people, soldiers, rebels and civilians were treated at the hospital. Once well enough to leave Irish prisoners were moved on initially to a Dublin prison or military barracks and then onwards to prison in Britain. Cathal Brugha was the last Irish prisoner to leave the hospital having only recovered from his wounds in August 1916. The hospital continued to treat the wounded of the First World War after the Rising, and was closed in 1919.