The long rock which claimed his life is in geological terms a volcanic dyke and provides the foundation for the castle. Some accounts suggest that he had contracted leprosy and was returning to seek a cure from a holy well. The history of Carrickfergus Castle spans some 800 years, it has seen many Kings and Earls pass through its main gates. It was from Carrickfergus that the Earl of Essex, acting Governor of Ulster, launched his attack on Rathlin Island in 1575, a strategic move carried out by Francis Drake and Henry Sydney which resulted in the massacre of 600 people who belonged to or were allies of the McDonnells. In retaliation Sorley Boy McDonnell attacked Carrickfergus killing over 100 of the garrison and taking their cattle and corn.