The British government went about boosting army numbers in WW1 through legislation. Faced with appalling casualty figures and a decline in voluntary recruiting, the British government introduced the first Military Service Act in January 1916, rendering all single men and childless widowers between the ages of 18 and 41 liable to conscription. The Military Service (No 2) Act then extended conscription to all men between these ages in June 1916, the age range being subsequently extended to 50 in April 1918. Provision for the conscription of men up to the age of 56 (and the extension of conscription to Ireland for the first time) if the need arose was also incorporated into the 1918 legislation, but never implemented. In addition, there was legislation in July 1917 to enable the conscription of French and Russian citizens residing in Britain.

Conscription was an unprecedented intrusion by the state into the lives of individual British citizens, for though often debated, compulsion had not been applied to the regular army since short-lived legislation in the early 18th century that had affected only debtors, vagrants and other marginal elements within society. The militia, raised entirely for home defense, had been subject to compulsion on occasions between 1757 and 1831, but the militia ballot had been deeply unpopular and the public had shown no support for conscription. Indeed, it was the voluntary system of enlistment that most differentiated the British army from those of the great continental powers.

The need to implement compulsion, therefore, represented one of the most significant indications of the impact of ‘total war’ upon the British state, its institutions and its communities between 1914 and 1918. It was not implemented without an agonized debate that grew in intensity, the last throw of the voluntary system being the failure of the so-called Derby Scheme between October and December 1915, by which men were encouraged to attest their willingness to serve if called upon to do so. Those conscripted could appeal to local military service tribunals for exemption from military service on the grounds of conscience, family circumstances, or by reason of employment in key occupations. The tribunals could either insist that the individual concerned enlist, defer entry, or they could exempt him. Composed mostly of local representatives of the ‘great and good’, though also including women, employers and representatives of organised labour, the tribunals have had a bad press. It has been suggested that tribunal members were unduly influenced by the military representatives of the War Office and especially hostile to exemption claimed on the grounds of conscience. In reality, only 16,500 claims for exemption were made on the grounds of conscience between 1916 and 1918 when compared, for example, to over a million exemptions granted on medical grounds in the last 12 months of the war alone.

Some 4.9 million men were enlisted in the British army between 1914 and 1918, of whom 2.4 million enlisted prior to the introduction of conscription and 2.5 million after it. It is calculated that only 1.3 million
men were actually conscripted.