<P> Unwilling to negotiate any understanding with Britain short of complete independence , the Irish Republican Army , the army of the newly declared Irish Republic , waged a guerilla war ( the Irish War of Independence ) from 1919 to 1921 . In the course of the fighting and amid much acrimony , the Fourth Government of Ireland Act 1920 implemented Home Rule while separating the island into what the British government 's Act termed `` Northern Ireland '' and `` Southern Ireland '' . In July 1921 the Irish and British governments agreed to a truce that halted the war . In December 1921 representatives of both governments signed an Anglo - Irish Treaty . The Irish delegation was led by Arthur Griffith and Michael Collins . This abolished the Irish Republic and created the Irish Free State , a self - governing Dominion of the Commonwealth of Nations in the manner of Canada and Australia . Under the Treaty , Northern Ireland could opt out of the Free State and stay within the United Kingdom : it promptly did so . In 1922 both parliaments ratified the Treaty , formalising independence for the 26 - county Irish Free State ( which renamed itself Ireland in 1937 , and declared itself a republic in 1949 ) ; while the 6 - county Northern Ireland , gaining Home Rule for itself , remained part of the United Kingdom . For most of the next 75 years , each territory was strongly aligned to either Catholic or Protestant ideologies , although this was more marked in the six counties of Northern Ireland . </P>
<P> Unwilling to negotiate any understanding with Britain short of complete independence , the Irish Republican Army , the army of the newly declared Irish Republic , waged a guerilla war ( the Irish War of Independence ) from 1919 to 1921 . In the course of the fighting and amid much acrimony , the Fourth Government of Ireland Act 1920 implemented Home Rule while separating the island into what the British government 's Act termed `` Northern Ireland '' and `` Southern Ireland '' . In July 1921 the Irish and British governments agreed to a truce that halted the war . In December 1921 representatives of both governments signed an Anglo - Irish Treaty . The Irish delegation was led by Arthur Griffith and Michael Collins . This abolished the Irish Republic and created the Irish Free State , a self - governing Dominion of the Commonwealth of Nations in the manner of Canada and Australia . Under the Treaty , Northern Ireland could opt out of the Free State and stay within the United Kingdom : it promptly did so . In 1922 both parliaments ratified the Treaty , formalising independence for the 26 - county Irish Free State ( which renamed itself Ireland in 1937 , and declared itself a republic in 1949 ) ; while the 6 - county Northern Ireland , gaining Home Rule for itself , remained part of the United Kingdom . For most of the next 75 years , each territory was strongly aligned to either Catholic or Protestant ideologies , although this was more marked in the six counties of Northern Ireland . </P>
when did ireland gain its independence from britain
when did ireland gain its independence from britain
December 1921
December 1921