Galloglass, from the Gaelic gallóglaigh for 'foreign warriors', were mercenaries from the Western Isles of Scotland who fought in the retinues of Irish magnates from the mid-13th century until the early 17th century. This work looks at the clan and family structures of the galloglass, their performance in battle, their weapons and armor and how these were made and by whom. The unique fighting skills and tactics of the galloglass are also studied, as well as how they were organized on the battlefield and their command structures and systems of rank.