Mellows is born at Hartshead Military Barracks, Ashton-Under-Lyne, Lancashire, England, to William Joseph Mellows, a British Army non-commissioned officer, and Sarah Jordan, of Inch, County Wexford. His family moves to 10 Annadale Avenue, Fairview, Dublin, in February 1895 when Sergeant Mellows is transferred there, however Liam remains in Wexford with his grandfather Patrick Jordan due to ill health. He attends the military school in Wellington Barracks in Cork and the Portobello garrison school in Dublin, but ultimately refuses a military career much to his father’s disappointment, instead working as a clerk in several Dublin firms, including the Junior Army & Navy Stores on D’Olier Street .
Mellows is introduced to socialism when he meets James Connolly at Countess Markiewicz’s residence, recuperating after his hunger strike. He is active in the Irish Republican Brotherhood (IRB) and is a founder member of the Irish Volunteers , being brought onto its Organising Committee to strengthen the Fianna representation. He is arrested and jailed on several occasions under the Defence of the Realm Act. Eventually escaping from Reading Gaol, he returns to Ireland to command the “Western Division” of the Irish Republican Army (IRA) during the Easter Rising of 1916.
Mellows leads roughly 700 Volunteers in abortive attacks on Royal Irish Constabulary
stations at Oranmore and Clarinbridge in County Galway and takes over the town of Athenry. However, his men are very badly armed and supplied and they disperse after a week, when British troops and the cruiser HMS Gloucester are sent west to attack them.
After this insurrection fails, Mellows escapes to the United States, where he is arrested and detained without trial in The Tombs in Lower Manhattan, New York, on a charge of attempting to aid the German side in World War I. After his release in 1918, he works with John Devoy and helps to organise Éamon de Valera’s fund raising visit to America in 1919–1920.
Mellows returns to Ireland to become Irish Republican Army “Director of Supplies” during the Irish War of Independence, responsible for buying arms. At the 1918 general election of December, he is elected to the First Dáil as a Sinn Féin candidate for both East Galway and for North Meath. He considers the Anglo-Irish Treaty as signed to be a betrayal of the Irish Republic. A conference of 9 TDs is deputed to meet privately on January 5, 1922 to resolve the dispute and to achieve a unified front by compromise. The four other anti-Treaty TDs say there is agreement but Mellows does not, and is seen thereafter by pro-Treaty TDs as one of their most implacable opponents. The following day the Dáil votes to approve the Treaty by a majority of 64 to 57.
Mellows is one of the more strident TDs on the approach to the Irish Civil War. In June 1922, he and fellow republicans Rory O’Connor, Joe McKelvey and Richard Barrett, among others, enters the Four Courts, which has been occupied by anti-Treaty forces since April. However, they are bombarded by pro-Treaty Free State forces and surrender after two days. Mellows has a chance to escape along with Ernie O’Malley, but does not take it. Imprisoned in Mountjoy Gaol, Mellows, O’Connor, McKelvey and Barrett are executed by firing squad on December 8, 1922, in reprisal for the shooting of TD Seán Hales. Mellows is buried in Castletown cemetery, County Wexford, a few miles from Arklow. An annual commemoration ceremony is held at his grave site, in which a wreath is laid by a member of the Liam Mellows Commemoration committee.
Mellows is commemorated by statues in Oranmore and Eyre Square in Galway, in the official name of the Irish Defence Forces army barracks at Renmore and in the naming of Mellows Bridge in Dublin. Mellows Avenue in Arklow is named in his honour. He is also commemorated in the names of two hurling clubs, one in Galway and one in Wexford, and by Unidare RFC in Ballymun and their “Liam Mellows Perpetual Cup.”