Edgar Rice Burroughs 
The Outlaw of Torn 

Set in 13th century England, the story concerns the fictitious outlaw Norman of Torn, who harried the country during the power struggle between King Henry III and Simon de Montfort. Raised to be a simple, brutal killing machine with a hatred of all things English, he is the best swordsman in all of England by the age of 17; by the age of 18, he has a large bounty on his head, and by the age of 19, he leads the largest band of thieves in all of England.