Sentence:  "Then those lands in the County of Cavan which was O'Rilie's country are all holden of the King ; and because the captainship or <WSD>chiefery</WSD> of O'Rilie is abolished by act of Parliament by Stat. 2d of Elizabeth, and also because, two of the chief  lords elected by the country have been lately slain in rebellion (which is an attainder in law), these lands are holden immediately of his Majesty. 
Meaning of the word marked with <WSD> tags:  The status or role of a chief; chieftainship.