Following the war of independence in the 1920s between the Irish Republican Army (IRA) and British forces, Ireland was divided in two. To the south, the Irish Free State emerged, with a Catholic majority, while six counties of Ulster, with a Protestant majority, remained under British sovereignty as Northern Ireland, with its capital in Belfast. However, part of the Catholic minority continued to defend the reunification of the island, a cause promoted by Sinn Féin. What has happened in Ireland since then? We tell you.