Founded in November 1914 by Fenner Brockway, editor of Labour Leader newspaper, and his wife Lilla, who suggested Fenner invite those who were not prepared to take part in military service to contact the newspaper. There was an immediate response with around 300 members. Some objected on religious grounds, such as the Quakers and others objected on political grounds.
Membership continued to grow and an office was opened in London in early 1915. Lilla had initially worked from home but at this point Clifford Allen took over. Clifford, a socialist, had previously been a manager on the Labour Party newspaper, the Daily Citizen. He was later sent to prison where he contracted tuberculosis of the spine. In December 1917 Clifford was released after 16 months.
NCF branches were established throughout the country, working to fight against conscription in the form of the proposed Military Service Bill. Members stated they would not serve or carry out any form of war work. The Derby scheme (after Lord Derby) was introduced, which aimed to persuade men to voluntarily enlist, but great pressure was put on men to do so. When the Military Service Bill was introduced the NCF launched a huge campaign against it. However on 2nd March 1916 conscription formerly began for single men between 18 and 41 years old. In June the same year it was extended to married men between 18-41 years.
Men could apply to be exempt by applying to a locally held tribunal. The NCF began keeping records of conscientious objectors, including details of their particular objection, their appearance at tribunals, courts martial and in some cases prison or Home Office Scheme work camps. Visits to those detained were also made.
The NCF began a weekly newspaper, The Tribunal and used this to highlight the plight of the conscientious objectors (COs), along with briefing MPs and Ministers. A number of COs were sentenced to death after a court martial, but these sentences were later commuted to 10 years imprisonment following widespread publicity from the NCF.