The 1st Battalion was serving in Ireland upon the outbreak of the war and was given orders to mobilise on 4 August, the day that Britain declared war on Germany. Part of the 15th Brigade, 5th Division the battalion left Belfast on 14 August and immediately embarked for France, where they became part of the British Expeditionary Force (BEF). They saw their first action of the war against the German Army at the Battle of Mons in August 1914. The 2nd Battalion was serving in Bombay, India in the 18th (Belgaum) Brigade, part of the 6th (Poona) Division, of the British Indian Army, upon the outbreak of war. The 2nd Battalion of the Norfolks fought in the Mesopotamian campaign. The treatment of prisoners after the fall of Kut al Amara in April 1916 mirrors that that would later befall the Royal Norfolks in the Far East during the Second World War.