Following the Flight of the Earls in 1607, the English crown seized Irish lands in Ulster and granted large parcels to English and Scottish "planters" on the condition that they build settlements and provide strongholds loyal to the King. Soon thereafter, plantation castles were built to govern and defend against a hostile native population. While in ruins, Monea Castle, west of Enniskillen, is the largest and best preserved castle.

 

While in ruins, Monea Castle, west of Enniskillen, is the most complete and best-preserved of all the Plantation castles of Ulster. Building commenced in 1616 by the Rector of Devenish, the Reverend Malcolm Hamilton. Shortly afterwards, in 1619, it was described by Pynnar as "a strong castle of lime and stone being 54 feet long and 20 feet broad". The bawn, comprising "a wall 9 feet in height and 300 feet in circuit" was added shortly before Hamilton was promoted to become Archbishop of Cashel in 1623. Like so many of Ulster's Plantation castles, the design of Monea reflects the Scottish origin of its builder. Three storeys high with tall attics, it has a rectangular plan with a pair of massive semi-cylindrical towers on the short west end. These towers are corbelled out at attic-floor level to carry diagonally placed square caphouses with crow-stepped gable roofs. The castle's only entrance lay on the south side of the north tower and led to a spiral stair giving access to the principal rooms, which were on the first floor and were illuminated by large windows with seats in the embrasures.

During the 1641 rebellion it was attacked by Rory Maguire, who "slew and murthered eight Protestants" here, but evidently failed to capture the castle. In 1688 it was occupied by Gustavus Hamilton, the Governor of Enniskillen, who died in 1691 having incurred enormous financial losses in the Williamite wars. His greatly impoverished wife and children continued to live at Monea, but had to sell the estate in 1704.