Usage patterns
〈人〉が将軍になるfor someone to become shogun
Tokugawa Ieyasu became shogun at the start of the Edo period.
将軍に任命されるto be appointed as general/commander
He was appointed as a general while still young.
将軍の座を継ぐto inherit the position of shogun
The son succeeded his father and inherited the shogunate.