Saint George (c. 275/281 – 23 April 303 AD), born in Lydda in Roman Palestine, was a soldier in the Roman army and was later venerated as a Christian martyr. Crusaders may actually have muddled up stories about St George and pictures of St Michael fighting against Satan represented as a dragon.
Saint George is somewhat of an exception among saints and legends, in that he is known and respected by Muslims.
The Colours of Saint George, or St George's Cross, are a white flag with a red cross, frequently borne by entities which claim him as patron - e.g. the Republic of Genoa and then Liguria, England, Georgia, Catalonia, and Aragon.