Irish Tricolour 6'x3' Heavy WeaveHeavy duty to suit flag pole The National Flag of Ireland (Irish: An Bhratach Nisinta), also known as the Irish tricolour is the national flag of the Republic of Ireland (Irish: Poblacht na hireann). The flag was adopted in 1919 by the Irish Republic during its war of independence, and subsequently by the Irish Free State (19221937), later being given constitutional status under the 1937 Constitution of Ireland, which established the Republic.