In Britain, conscription resulted in the calling up of nearly every physically fit man in Britain—six of ten million eligible. Of these, about 750,000 lost their lives. Most deaths were to young unmarried men; however, 160,000 wives lost husbands and 300,000 children lost fathers. Conscription during the First World War began when the British government passed the Military Service Act in 1916. The act specified that single men aged 18 to 40 years old were liable to be called up for military service unless they were widowed with children or ministers of a religion. There was a system of Military Service Tribunals to adjudicate upon claims for exemption upon the grounds of performing civilian work of national importance, domestic hardship, health, and conscientious objection. The law went through several changes before the war ended. Married men were exempt in the original Act, although this was changed in June 1916. The age limit was also eventually raised to 51 years old. Recognition of work of national importance also diminished, and in the last year of the war there was some support for the conscription of clergy. Conscription lasted until mid-1919. Due to the political situation in Ireland, conscription was never applied there; only in England, Scotland and Wales.. How many years were added onto the Military Service Act after the original span of 18 - 40 was increased?