After the death of the Irish Prime Minister, Michael Collins, in the Irish Civil War, William Thomas Cosgrave became the Chairman for the Irish Provisional Government, and was the first president of the Executive Council of the Irish Free State. He led Ireland through the turbulent post-war years and the Great Depression.

After Ireland had won a degree of independence from Britain during the Anglo-Irish War, and before the Civil War which divided the country, Cosgrave had been appointed the Minister for Local Government. He was successful in establishing Ireland's government and rallying the Irish people against the British authorities. He organised assistance and homes for the poor and established the Sinn Féin courts, which rejected English law and imposed new punishments. The courts were widely recognised throughout Ireland, and when the RIC¹ tried to shut the courts down, they continued underground, even after judges were arrested.

After the Civil War, in April, 1923, Cosgrave founded the Cumann na nGaedhael² party with the surviving pro-Treaty Sinn Féin members. The new Sinn Féin, under de Valera, was formed around the army of the republic. Cosgrave ruled almost unopposed, as the members of the anti-Treaty Sinn Féin refused to take the Oath of Allegiance to be able to take their seats in parliament.

Cosgrave's skill as a politician and his contribution to the founding of Ireland as a modern state can be seen in the steps he took to ensure that Ireland remained a free republic in the turbulent years after the Irish War of Independence and the Irish Civil War, then through the Depression. His efforts greatly contributed to keeping Ireland from becoming a military dictatorship like many newly-founded states which faced civil war. Cosgrave's confrontation of the 'army mutiny' and his establishment of an unarmed police force kept the new nation from descending into martial law. Before the Stock Market Crash in 1929 the Irish economy was strong, despite the financial toll the war took on the country. The level of export of agricultural produce in 1926 was not equaled until 1960, and Cosgrave's government created the Electricity Supply Board in 1927, completed the Shannon Hydro-Electric scheme and established a national radio. Ireland won international recognition as a free state and gained membership in the League of Nations. WT Cosgrave retired from politics in 1944.