In 1800, Ireland was politically joined to Great Britain through the Acts of Union. Though the two countries had been in personal union since 1541, meaning they shared the same monarch, these Acts officially rendered Ireland a part of Great Britain.
Although the Acts were intended to quell expressions of Irish nationalism, they had the reverse effect, and throughout the nineteenth century protests occurred as Irish nationalists demanded the Acts be repealed and a self-governing Kingdom of Ireland be established. The Home Rule movement, as it came to be known, continued to be an important part of Irish politics until the end of the Great War.
In the 1880s, the Liberal British Prime Minister William Ewart Gladstone attempted to pass Home Rule bills through Parliament; the text of his famous three-hour speech can be read here. From 1886 to 1920 a series of Home Rule acts were proposed in the British Parliament, eventually resulting in the Partition of Ireland and the creation of the Republic of Ireland.