King James‘s advisors used the Flight of the Earls in 1607 as an excuse to confiscate land, and grant it to those who would undertake to settle and support the royal claim.
The undertakers, mainly English and Lowland Scots were to bring tenants to live and work on the land found themselves amongst a hostile native population, and had to build defensive dwellings to live in.
Woodkearne were soldiers who fought for the Irish chieftains and left leaderless after the Flight of the Earls they took to the woods and mountains During the early years of Plantation they tried to prevent planters from settlement. Murders and robberies especially of cattle were commonplace.
Servitors were men who had served the monarch as an official or soldier in Ireland and were in turn granted land.
The deserving Irish were those native Irish who swore allegiance to the crown and were rewarded with land ownership.
The plantation castles are now all ruinous however they still reflect the varied origins of their builders from the troubled Scottish borders where castles were still in use to the south of England where the spread of renaissance ideas was already creating new classical fashions.