When war was declared two pacifists, Clifford Allen and Fenner Brockway, formed the No-Conscription Fellowship (NCF), an organisation that encouraged men to refuse war service. The group received support from public figures such as Philip Snowden, Bruce Glasier, Robert Smillie, and Rev. John Clifford.

Over 3,000,000 men volunteered to serve in the British Armed Forces during the first two years of the war. Due to heavy losses at the Western Front the government decided to introduce conscription (compulsory enrollment) by passing the Military Service Act. At first only single men were called up but by 1918 married men of fifty were being conscripted into the army.

After the passing of the Military Service Act, the No-Conscription Fellowship mounted a vigorous campaign against the punishment and imprisonment of conscientious objectors. About 16,000 men refused to fight. Most of these men were pacifists, who believed that even during wartime it was wrong to kill another human being. About 7,000 pacifists agreed to perform non-combat service. This usually involved working as stretcher-bearers in the front-line, an occupation that had a very high casualty-rate. Over 1,500 men refused all compulsory service. These men were called absolutists and were usually drafted into military units and if they refused to obey the order of an officer, they were court-martialled.