 When the Torstenson War between Sweden and Denmark broke out in 1643, De la Gardie returned to his native Sweden, and learned about warfare under the command of Field Marshal Gustav Horn.Early on during the reign of Queen Christina (1644–1654) De la Gardie became the queen's favourite at only 23 years of age.Being, reportedly, both well-mannered and good looking might have helped De la Gardie to gain the queen's favour.