Northern Ireland was governed by the Ulster Unionist Party from 1922-1972. James Craig, its first prime minister, said it was a Protestant country. The Irish Free State got a new constitution in 1937, which created its government. In 1949, Ireland left the British Commonwealth and became the Republic of Ireland (sometimes just called Ireland). In 1969, violence was growing in Northern Ireland between the Nationalist Catholics and Unionist Protestants. The Provisional IRA formed to defend Catholics and unite Ireland. From 1969 until 1998, there was constant fighting (The Troubles) between the Provisional IRA and the UK Army.