He made his military debut at the Battle of Dettingen, where his father led his country's forces into battle, while his most famous victory was preceded by the defeat of Henry Hawley at the Second Battle of Falkirk and took place in a year which had previously seen him fail to relieve Tournay after it was besieged by Marshal Saxe.  
The Convention of Kloster-Zeven was signed following this man's defeat against d'Estr?s at Hastenbeck, while another one of his defeats, at the Battle of Lauffeld, was a rematch with a man who had defeated him two years earlier. He made his military debut at the Battle of Dettingen, where his father led his country's forces into battle, while his most famous victory was preceded by the defeat of Henry Hawley at the Second Battle of Falkirk and took place in a year which had previously seen him fail to relieve Tournay after it was besieged by Marshal Saxe.  FTP, name this son of George II who in 1746 crushed the Young Pretender's rebellion at Culloden Moor, the namesake of a "gap" in the Appalachian Mountains.
The Convention of Kloster-Zeven was signed following this man's defeat against d'Estr?s at Hastenbeck, while another one of his defeats, at the Battle of Lauffeld, was a rematch with a man who had defeated him two years earlier.
Prince William Augustus, Duke of Cumberland (accept either underlined answer)