In the 1930s, the Irish Taoiseach (similar to a prime minister) was Éamon de Valera. de Valera worked to make a new constitution (set of laws) for Ireland. He wanted to make Ireland independent from Britain. Ireland had its own government, but Britain still controlled Northern Ireland, and had naval ports (called treaty ports) in Ireland. de Valera wanted this control to stop. Chamberlain wanted Ireland to support Britain if there was a war because he knew that without Irish help, defending the Atlantic Ocean would be difficult. Chamberlain and his Secretary of State, Malcolm MacDonald made an agreement to give the treaty ports back to Ireland, but hoped that British warships might use them in the war.