Éamon de Valera was a dominant political figure in 20th Century Ireland, a primary leader during the struggle for independence from Britain, and the leader of the anti-Treaty forces during the Irish Civil War.
De Valera joined the Irish Volunteers1 on 25 November, 1913. During the Easter Rising in 1916 he held Boland's Mill in Dublin until Pádraig Pearse, the leader of the Rising, called for the Volunteers to surrender one week later. He was arrested and sentenced to death, but the sentence was commuted to life imprisonment, and he was later released under amnesty. The fact that he was born in Manhattan and therefore had American citizenship has been a rumoured reason he wasn't executed along with Pádraig Pearse and the other military leaders, but in reality, the question of his citizenship only postponed the decision until such a time that the public opinion of Britain's response to the uprising made further executions impossible. He thereby enjoyed political prestige as the only surviving commander of a military post to survive the 1916 Easter Rising. He was elected to parliament while still in prison.
Sinn Féin and Dáil Éireann
De Valera was elected to the Sinn Féin, which was a previously small monarchical party which had been wrongly condemned by the British as being behind the Easter Rising, and was subsequently taken over by the survivors of the rebellion to capitalise on the party's notoriety. Sinn Féin became popular with the Irish as the public's condemnation of the rising gave way to sympathy and outright anti-British sentiments after the harsh treatment of the rebels and the execution of the leaders, and with the threat of conscription in 1918.
In 1918 the Sinn Féin members of parliament2 formed an Irish government called Dáil Éireann (Assembly of Ireland) or First Dáil, which declared Irish independence from Britain, formally ratifying the 1916 Proclamation of Independence in January 1919. The Aireacht (Ministry) was headed by the Príomh Aire (President of Dáil Éireann), or the Prime Minister of Ireland. Cathal Brugha was the Príomh Aire until de Valera, who had been rearrested in May 1918, escaped from Lincoln Gaol with Michael Collins' help, and took over the office.
Anglo-Irish Treaty and the Irish Civil War
The Irish War of Independence, also called the Anglo-Irish War, lasted from January 1919 to July 1921. When the war ended and Ireland and Britain entered negotiations, de Valera sent plenipotentiaries to England in his place. He had the Dáil Éireann upgrade his office from Prime Minister to President of Ireland, and argued that as the head of state, he should not attend the peace conference in the absence of his counterpart, King George V. Under severe threat from Lloyd George, the treaty was signed without de Valera's approval. Today, it is widely agreed that de Valera didn't expect to approve the treaty, as he expected an outcome he could disown if necessary, and furthermore that he deliberately kept out of the negotiations so that he wouldn't be identified with the outcome.
After the treaty was signed, a new provisional government was established, the treaty was ratified in the new Dáil by a 64 to 57 margin, and the radical republicans under de Valera split from the Sinn Féin, along with anti-Treaty units of the IRA, who became the 'irregulars'. De Valera and the other radical republicans saw the treaty, especially the oath swearing fealty to the Crown, as a betrayal of the cause of independence they'd fought for.
Independently of de Valera, the irregulars took control of the Four Courts building in Dublin, and the Civil War began, nominally pitting de Valera against Michael Collins. De Valera eventually ceded the war, by placing an announcement in newspapers:
Soldiers of the Republic! Legion of the Rearguard! The Republic can no longer be defended successfully by your arms. Further sacrifice of life would be in vain, and continuance of the struggle in arms unwise in the National interest. Military victory must be allowed to rest for the moment with those who have destroyed the Republic.
De Valera's Government
After the cessation of the civil war, WT Cosgrave formed a new independent government, and ruled until 1932, when de Valera's new party came into power. De Valera's Sinn Féin party split again in March 1927, and de Valera formed Fianna Fáil ('Soldiers of Destiny') - The Republican Party.
Fianna Fáil came into power in 1932 and Éamon de Valera was once again President of the Executive Council. De Valera immediately introduced a bill to remove the Oath of Allegiance from the Constitution3, and when the Senate held it up for more than a year he removed the Senate as well. Under de Valera's leadership the government released republican prisoners, lifted the ban on the IRA and stopped paying land annuities to Britain, which heralded in the 'Anglo-Irish Trade War', or the 'economic war' from 1933 to 1938. Britain imposed a 20 per cent sanction on all goods entering Britain from Ireland. This forced Irish farmers to switch from grazing to tillage farming techniques to only grow what could be sold nationally, and caused widespread unemployment. By the 1938 Trade Agreement Ireland had lost almost sixty million pounds, but de Valera had gained the right of duty-free entry to the British market while protecting Ireland's own, and reacquired the naval ports lost in the Anglo-Irish Treaty of 1921, which proved essential for Ireland to maintain her neutrality during World War Two.
League of Nations
De Valera impressed international audiences in September 1932 when he presided over a meeting of the League of Nations and spoke about Japan's defiance of the League's Covenant, impressing the need of all nations to respect the Covenant and the other nations of the League. His speech could also be seen as an implied criticism of Britain's imposing of partition on Ireland, which was also supposedly a flouting of the Convention.
On 1 May, 1937 de Valera published his new constitution, Bunreacht na hÉireann ('The Constitution of Ireland'), and it was approved on 14 June. The new constitution officially named Ireland Éire in the Irish language, proclaimed Irish as the first official language and laid claim to the entire island of Ireland, its territorial seas and surrounding islands - in effect ignoring the partition. It mentioned Catholicism's 'special place' in Irish culture, but also mentioned other religious groups, including other Christians and Jewish synagogues. De Valera's constitution is still considered fair and advanced for its time, and it has been used as a model in several other countries.
Éamon de Valera served as the President of Ireland, on and off, until 1973, when he was 91 years old. His early life was one of controversy, and near the end of his life he expressed regrets about his legacy, reflecting at the age of 85 that 'it's my considered opinion that in the fullness of time, history will record the greatness of Collins and it will be recorded at my expense'. He is also quoted as referring to Cosgrave and his ministry as 'magnificent', as early as 1932. While he was considered by many to be 'the most influential Irish leader of the twentieth century', he was also regarded as being an 'idealistic but flawed' leader.