Okay, kiddo, let's talk about Irish Republican Legitimism. You know how some people in Ireland want the country to be united and not divided into two parts (Northern Ireland and the Republic of Ireland)? Well, those people are sometimes called Republicans.
But there are also some Republicans who believe that the only legitimate government of Ireland is the one that was formed in 1919, during a time when Ireland was fighting for its independence from Britain. They believe that this government, called the Irish Republic, is the only one that truly represents the Irish people and that any other government that has come after it is illegitimate.
These Republicans see the partition of Ireland and the creation of Northern Ireland as a violation of Ireland's sovereignty and believe that the British government has no right to interfere in Irish affairs. They also believe that violence is sometimes necessary to achieve their goals, including the overthrow of the current governments in both Northern Ireland and the Republic of Ireland.
Overall, Irish Republican Legitimism is a political and ideological movement that seeks to unify Ireland under a government that is seen as the only legitimate one. It is a complex and controversial topic, but it boils down to a belief in the importance of Irish independence and sovereignty.