 On 1 May 1169 , an expedition of Cambro @-@ Norman knights with an army of about six hundred landed at Bannow Strand in present @-@ day County Wexford . It was led by Richard de Clare , called Strongbow due to his prowess as an archer . The invasion , which coincided with a period of renewed Norman expansion , was at the invitation of Dermot Mac Murrough , the king of Leinster . 
