When Hugh de Lacy received the Kingdom of Meath in 1172, the process of settlement and sub-infeudation began, though it took years for Anglo-Norman influence to reach as far west as Athlone. The town’s original Anglo-Norman grantee, Geoffrey de Costentin, received a cantred in Connacht adjoining Athlone in 1200, and likely constructed an earth and timber castle here between 1191 and 1199. The Annals of Loch Cé record that in 1199, Cathal Crobhderg burned the ‘bódhún’ (bawn or cow fort) of Athlone and killed many of its defenders, suggesting either a ringwork earthwork or possibly the bailey of a motte castle. This fortification formed part of the western frontier of the Liberty of Meath, alongside other motte castles at Granard, Kilbixy, and Rathconrath.

There’s intriguing evidence that de Costentin may have simply reused an existing Gaelic fortification rather than building entirely anew. The O’Conors had maintained their own earth and timber castle at Athlone, and when John de Grey, Bishop of Norwich, built a new stone castle in 1210, the annals specifically mention it was constructed ‘instead of Ua Conchobhar’s castle’. However, this doesn’t rule out an intermediate motte construction, as Anglo-Normans frequently built mottes atop existing ringforts and settlements. The debate over whether de Costentin built on the east or west bank of the Shannon continues, though historian G.H. Orpen believed traces of the original motte could still be detected beneath the later stone castle.

King John’s visit to Ireland in 1210 marked a pivotal moment for Athlone’s development. John de Grey, appointed as justiciar to improve colonial administration, recognised Athlone’s crucial position and apparently envisioned it sharing administrative duties with Dublin. His ambitious plans led to the construction of both a new stone castle and bridge in 1210, replacing the earlier fortifications. This sequence of building; from Gaelic earth and timber fort to Anglo-Norman motte to stone castle; reveals how successive powers recognised and reinforced Athlone’s vital position controlling passage across the Shannon between the settled lands of Meath and the contested territories of Connacht.