Blamore was brother to Sir Bleoberis de Ganis, cousin to Lancelot, and a knight of the Round Table. Of the two brothers, Blamore was accounted the better man of arms. Blamore and Bleoberis once arraigned King Anguish of Ireland for the death of a cousin of theirs. Blamore was the one who fought the actual trial by combat against Anguish's champion, Sir Tristram. Defeated, Blamore tried to insist on death rather than surrender. Bleoberis seconded his brother's request, but Tristram and the judges refused to allow it.

And then, by all their advices ... the two brethren were accorded with King Anguish, and kissed and made friends for ever. And then Sir Blamore and Sir Tristram kissed together, and there they made their oaths that they would never none of them two brethren fight with Sir Tristram, and Sir Tristram made the same oath. And for the gentle battle all the blood of Sir Launcelot loved Sir Tristram for ever.

Malory mentions Blamore several more times - fighting at the tournament of the Castle of Maidens, joining a quest to find Tristram, taking a fall from Sir Palomides at Duke Galeholt's tournament in Surluse. Blamore and Bleoberis were two of the guests at Guenevere's small dinner party when Sir Patrise was poisoned. Later, they followed Lancelot into exile, and Blamore was made Duke of Limosin in Guienne.