Official Flag of Ireland

Ireland’s flag has possessed a lasting relevance and is rich in Irish history. This flag is known as that of the "Tricolour," the national flag of the Republic of Ireland. The tricolor flag of Ireland was introduced by Thomas Francis Meagher in 1848, when it was officially recognized as it was first unfurled.
This flag has three equal stripes that illustrates the Irish political landscape.

Green — signifying Irish Catholics and the cause of the republic

White — representing the hope for peace between them

Orange — standing for Irish Protestants

Orange is associated with Northern Irish Protestants because of Willliam of Orange (William III), the King of England, Scotland, and Ireland who in 1690 defeated the deposed King James II, a Roman Catholic, in the fateful Battle of the Boyne near Ireland's capital of Dublin. William's victory secured Protestant dominance over the island. Sometimes called Orangemen, Protestants in Northern Ireland celebrate the anniversary of the battle each July 12th.

Thomas Meagher on the meaning of the Irish flag said, "The white in the center signifies a lasting truce between the Orange and the Green; and I trust that beneath its folds the hands of the Irish Protestant and the Irish Catholic may be clasped in heroic brotherhood."