The St George's cross the national flag of England and has been since about 1277.
The banner of St George, was adopted for the uniform of English soldiers possibly in the reign of Richard the Lionheart, and later became the flag of England.
Although both Edward I and Edward II flew the St George banner in their wars against Scotland, it was not until the reign of Edward III that St George became the Patron Saint of England.
During Edward 3rd campaigns in France in 1345-49, pennants bearing the red cross on a white background were ordered for the king's ship and uniforms in the same style for the men at arms. When Richard 2nd invaded Scotland in 1385, every man was ordered to wear 'a signe (sic) of the arms of St George', both before and behind.