In 1914, Britain had the only army that was entirely made up of volunteers. Every other country used conscription to swell its army's size.
In Britain, supporters of conscription argued that young men had a duty above all else to defend their country. Those against conscription argued that it had not been used in Britain before and meant another increase in the power of the state at the cost of individual liberty.
Faced with the reality of a long war with high casualties, the UK government passed the Military Service Act in January 1916, which began conscription for single men from 18 to 41 years old.
In May 1916 conscription was extended to married men and by 1918 men up to the age of 51 were being conscripted - they were forced to join.
The Military Service Act of 1916 made allowances for some men to be exempt (excused) from military service. The measures included ill health or being engaged in vital war work such as coal mining. The most controversial exemption from military service was refusal to fight on grounds of conscience. These men were known as ‘conscientious objectors’. They claimed exemption on grounds of their pacifist, political or religious beliefs.