In the course of this investigation we will attempt to answer the following question: “To what extent did the Anglo-Irish Treaty lead to the outbreak of the Irish Civil War in 1922?” The examination of the number of issues contained in the Anglo-Irish Treaty signed in 1921, which caused disagreements; the most obvious terms, namely the oath of allegiance to the British crown, the partition of Ireland into North and South and the exit of the nationalist movements, will be brought to a decisive conclusion. Furthermore, the emphasis placed on the period between the date of the signature of 1921 and the beginning of the Civil War in mid-1922. To reach an accurate conclusion, a thorough evaluation is needed that includes the origin, purpose, value and limitation, as seen in Section C, of ​​the following sources; The Irish Civil War 1922-23 by Peter Cottrell and Tim Pat Coogan The Irish Civil War will be conducted to find each source responsible. Furthermore, an in-depth analysis of the two books will clarify their importance for the investigation. The Anglo-Irish Treaty was agreed between representatives of Sinn Fein (the equivalent of the Irish Republican Party) and the British government on 6 December 1921 (Coogan, Morrison 24). The signing of the Treaty sparked hostile debate in the Dail (Irish Parliament) before it was accepted by a slight majority, 64 in favor to 57 against, in January 1922 (David). Sinn Féin divisions spilled over into nationalist movements and the ranks of the Irish Republican Army (IRA) (Cottrell 30, Walsh). After the treaty was agreed, Éamon de Valera resigned as President of the Irish Republic and failed to do so. be re-elected at the 1922 general election (Leeson). Ah...... middle of paper...... Pub., 2008. Print.Dorney, John. "The Irish Civil War: A Brief Overview". Irish history. Np, 02 July 2012. Web. 01 December 2013. .Leeson, David. "Irish Civil War". The Irish War RSS2. WordPress, 2011. Web. 01 December 2013. Turner, David P. “The Treaty Debates of 1922 – 3.” 1916 Rebellion Walking Tour. Np, nd Web. 1 December 2013. Turner, David P. “Why There Was a Civil War in Ireland.” 1916 Rebellion Walking Tour. Np, nd Web. 01 December 2013. Walsh, Paul V. "The Irish Civil War 1922-1923." The Irish Civil War 1922-1923. Np, 11 December 1998. Web. 01 December. 2013. .