G. A. Henty 
Bravest of the Brave [PDF ebook] 
Or, with Peterborough in Spain

In 1705, only a few years after being released from the Tower of London, where he was imprisoned for his involvement in a political scandal, Charles Mordaunt, the 3rd Earl of Peterborough, came back into the favor of the court and was appointed as the leader of a large regiment of Dutch and English soldiers sent to fight in Spain. An account of this conflict is interwoven with a coming-of-age story of young Jack Stilwell, who also aids in the battle.