De Valera was born in New York City in 1882 to Irish parents. He was educated in Ireland and joined the Irish Republican Brotherhood (IRB) at an early age. He participated in the Easter Rising of 1916, which was a failed rebellion against British rule in Ireland. De Valera was sentenced to death for his role in the Rising, but his sentence was commuted to life imprisonment. He was released from prison in 1917.
After his release from prison, de Valera became one of the leaders of the Irish Volunteers, the military wing of the IRB. He played a leading role in the Irish War of Independence, which resulted in the establishment of the Irish Free State in 1922. De Valera was elected President of the Sinn Féin party in 1917, and he served as President of the Irish Republic from 1919 to 1922.
De Valera opposed the Anglo-Irish Treaty of 1921, which established the Irish Free State as a dominion within the British Empire. He believed that the Treaty was a betrayal of the Irish Republic and led the anti-Treaty side in the Irish Civil War. The Civil War was a bitter and bloody conflict, and de Valera was eventually defeated. He was captured by government forces in 1923 and imprisoned for over a year.
After his release from prison, de Valera founded the Fianna Fáil party in 1926. Fianna Fáil won the general election in 1932, and de Valera became President of the Executive Council (the equivalent of Prime Minister). He served as President of the Executive Council/Taoiseach until 1948, and again from 1951 to 1954 and 1957 to 1959.
De Valera was a controversial figure, and he is still a divisive figure in Irish politics today. He was a passionate Irish nationalist, and he was determined to achieve Irish independence. He was also a republican, and he believed that Ireland should be a republic, not a dominion within the British Empire. De Valera was a complex and contradictory figure, but there is no doubt that he was one of the most important figures in Irish history.