MacCabe derives from the Irish Mac Caba, from caba meaning "cape" or "cloak". The family are thought originally to have been a branch of the MacLeods of Harris in the Hebrides. The came to Ireland from there in the mid-fourteenth century to act as gallowglasses (mercenaries) to the O'Reillys and the O'Rourkes, the ruling families in the kingdom of Breffny, the territory now part of counties Longford and Cavan. They became completely hibernicized and adopted the customs and practices of the Irish, including internecine war; having established themselves in neighbouring Fermanagh by the fifteenth century, they continued the struggle for control with the Maguires up to the final catastrophe of the seventeenth century. The surname also became prominent in other adjoining counties, in particular Co. Monaghan.