Fanad came under the control of the O’Breslins who were descended from Congel Cennemigher's son. During this era, there are records of attacks by Vikings on Fanad– specifically in Mulroy Bay at Kinnaweer near Milford in 921 AD. Late medieval period The power of the O'Breslins in Fanad lasted until sometime after 1263 when the Chieftains of Tir Conaill, the O’Donnells, granted the sub-chieftaincy of Fanad to the MacSweeneys (Gaelic: MacSuibhne) in return for their support of certain O’Donnell families in their struggle for chieftaincy of the clan. The MacSweeneys who were galloglasses, (mercenary warriors) from Scotland, were responsible for the building of the castle and the Carmelite Monastery at Rathmullan at the end of the 16th century. The MacSweeneys were also responsible for the building of the tower house at Moross on the upper stretches of Mulroy Bay in about 1532. 17th and 18th centuries The power of the MacSweeneys as Lords of Fanad ended with the Flight of the Earls in 1607 and the subsequent Plantation of Ulster, though they continued to hold some lands in Fanad as proprietors until the 1641 rising, following which all remaining MacSweeney lands were confiscated. The "hereditary commandery" of Fanad remains in the MacSweeney's families.Leabhar Clainne Suibhne Lands in Fanad were granted principally to servitors (Crown servants including veterans of the Nine Years War). Settlers noted in the 1654 Civil Survey include Richard Perkins at BelliclanmcCallen (sic), William and David Lyne at Bunintyne (Bunnaton?), John Rowly at Ballymastocker, Craveross (Croaghross?) and Magherawarden, Thomas Stewart at Carlan, Knockbrack and Drumfad, William Patton at Croghan, Colin and Patrick Campbell at Moross and Luke Ashe at Ballyhork. Some lands at Tullynadall were granted to the Provost and Fellows of Trinity College, Dublin. Rathmullan was initially granted to Sir Ralph Bingley but was soon passed to his son-in-law, Bishop Knox. Rathmullan was incorporated as a town and in 1618, Knox modified the Carmelite Friary to serve as a manor house. It remained as the residence of the Knox family until the late eighteenth century. Also notable at this stage was the building of the Church of Ireland in Rosnakill in 1693. Despite the plantation, Fanad retained its majority native population and Gaelic ways and Irish remained the principal spoken language of the peninsula – a situation that remained generally unchanged until the mid 19th century. The 18th century saw the introduction into Fanad of rural industry