Battle of the Castellum Guinnion

Nennius’s Historia Brittonum (c. 830) preserves the earliest account of Arthur’s Twelve Battles, portraying him as dux bellorum and linking him for the first time to the victory at Mount Badon.

Arthur’s Insignia, said to bear the image of St. Mary or the cross of Christ, symbolized divine protection in battle, though early sources likely intended the emblem to appear on his shield rather than on his shoulders.