In 1270, Robert De Muscegros built the first defensive fortress, known as a motte and bailey castle. These lands were later granted to Thomas de Clare, who built the first stone structure on the site. At this time Bunratty town had grown to a population of 1,000.
n 1318, Thomas's son Richard de Clare (new holder of the castle) was killed in the Battle of Dysert O'Dea during the Irish Bruce Wars 1315-1318. The castle and town were completely destroyed by the victorious O'Briens. n 1332, soon after being restored for the King of England, the castle was once again razed by the Irish Chieftains of Thomond under the O' Briens. The present structure was completed by the MacNamara family around 1425 but 50 years later was in the hands of the O'Briens, the most powerful clan in Munster. The castle was never really built by the McNamara clan, it was just completed by them.