 A significant body of these Irishmen later used the military experience gained in the American Civil War to fight against British forces with the goal of establishing an Irish Republic as members of the Irish Republican Brotherhood, the Fenian Brotherhood and Clan na Gael.In addition very large numbers of Scots-Irish Protestants were involved in the American Civil War, especially the Confederacy.Irish immigration to the United States has taken place since colonial times (such as John Barry of the U.S. Navy, while Andrew Jackson was partially Scots-Irish).