The Military Service Act was a landmark piece of legislation passed by the British government in response to the urgent need for more soldiers during World War I. As the war progressed, the initial volunteer army had begun to shrink, and casualties soared, prompting the government to reconsider its stance on conscription. The Act mandated that all able-bodied men aged between 18 and 41, who were not married or widowed with dependents, must register for military service. This move was controversial, stirring debates about individual rights and government responsibility in wartime. Proponents argued that conscription was essential to maintain adequate troop levels, while opponents raised concerns about fairness and the implications for personal liberties.

The Act was accompanied by a significant propaganda campaign aimed at encouraging enlistment and framing the war as a noble cause. Notably, the government had already introduced the Derby Scheme—a system with limited success that encouraged volunteers in late 1915. However, it became increasingly clear that voluntary enlistment alone would not meet the military's needs. The government's response was swift; the introduction of conscription was necessary to stabilize the army’s diminishing ranks. Following months of discussions and public debates, the Act came into effect, effectively changing the dynamics of Britons' lives amidst World War I.