Ligdan Khan
Oboi officially started his military career in 1634 during the reign of Hong Taiji as a junior officer in the Banner's cavalry guard unit in which capacity he distinguished himself many times in battle against Ming forces and was renowned for his personal bravery. For this, he was granted a hereditary commission as captain of a company ("niru i janggin"). In 1633 and 1634 he took part in campaigns against the Chahar Mongols, whose leader Ligdan Khan submitted to the Manchus in 1635.