St. George is also the patron saint of Ethiopia, although there isn't a cross contained within their flag.
One of the most famous invocations of St. George is in William Shakespeare's play Henry V:
"I see you stand like greyhounds in the slips,
Straining upon the start. The game's afoot;
Follow your spirit: and upon this charge,
Cry — God for Harry! England and Saint George!"
Happy Birthday, Bill.
Shakespeare's birthday is also celebrated today, April 23rd, St. George's day. Although there is no documentary evidence of his birthdate, it is known that he was baptised on April 26th, 1564. So, a birthdate three days earlier is possible.
It is also known that he died on April 23rd 1616.