He was killed while commanding his forces at the Battle of Dysert O'Dea near the modern town of Ennis in County Clare.
According to legend, the day before his death, Richard de Clare beheld a woman dressed in white on the river's edge washing bloody clothing and armor.
The next day, he lay dead with his clothes caked in blood on the battlefield of Dysert O'Dea.
As well as the stewardship of the Forest of Essex, Thomas' estate included numerous properties in Ireland.
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