The British Parliament passed the Government of Ireland Act 1914, known as the Home Rule Act, on 18 September 1914 with an amending Bill for the partition of Ireland introduced by Ulster Unionist MPs, but the Act's implementation was immediately postponed by the Suspensory Act 1914 due to the outbreak of the First World War in the previous month. The majority of nationalists followed their IPP leaders and John Redmond's call to support Britain and the Allied war effort in Irish regiments of the New British Army, the intention being to ensure the commencement of Home Rule after the war. However, a significant minority of the Irish Volunteers opposed Ireland's involvement in the war. The Volunteer movement split, a majority leaving to form the National Volunteers under Redmond. The remaining Irish Volunteers, under Eoin MacNeill, held that they would maintain their organisation until Home Rule had been granted. Within this Volunteer movement, another faction, led by the separatist Irish Republican Brotherhood, began to prepare for a revolt against British rule in Ireland.