Likely a reference to the Government of Ireland Act 1914 (Home Rule Act), which was approved by the British Parliament in May 1914 and received Royal Assent on September 18, 1914. The Act gave Ireland home rule with an Irish Parliament responsible for domestic affairs, within a federal United Kingdom. On the same day, however, implementation of the Act was postponed for a year; it would be extended multiple times during the war. On September 15, John Redmond (1852–1928), leader of the Irish Parliamentary Party, a proponent of Home Rule, nevertheless encouraged all his fellow countrymen to fulfill their duty and “take their place in the firing line in this contest.” He established an Irish Corps within the British army. A rival private army, the Ulster Volunteer Force, whose members opposed Home Rule, also fought under the British flag.

Grayson, Richard S. “Ireland.” In 1914–1918–online. International Encyclopedia of the First World War, edited by Ute Daniel, Peter Gatrell, Oliver Janz, Heather Jones, Jennifer Keene, Alan Kramer, and Bill Nasson. Freie Universität Berlin, 2014–. Article published October 8, 2014. https://encyclopedia.1914-1918-online.net/article/ireland.