From Tolkien Gateway

Bellomarius was the greatest dragon-slayer that the realm of the Middle Kingdom had ever known. He was said to be the maternal great-great-grandfather of Augustus Bonifacius, who was the king of the Middle Kingdom when Farmer Giles lived in the realm. He had also owned a famous sword called Caudimordax which had languished in the king's armoury. When Farmer Giles chased off a giant that had come to the village of Ham, the king made a present of the sword to the rustic. Thus, in a sense, Giles was the heir of Bellomarius.[1]