In 1757, Guy Carleton was made a lieutenant colonel and served as part of the Army of Observation made up of German troops designed to protect Hanover from French invasion. The army was forced to retreat following the Battle of Hastenbeck and eventually concluded the Convention of Klosterzeven, taking them out of the war. After the convention was signed, Carleton returned to Britain. In 1758 he was made the lieutenant colonel of the newly formed 72nd Regiment of Foot. James Wolfe selected Carleton as his aide in the 1758 attack on Louisburg. King George II declined to make this appointment, possibly because of negative comments he made about the soldiers of Hanover during his service on the Continent.