In 235, Sima Yi was promoted to Grand Commandant and had the number of taxable households in his marquisate increased. In the same year, when the Shu general Ma Dai led troops to invade Wei, Sima Yi sent Niu Jin to lead Wei forces to resist the invaders. Niu Jin defeated Ma Dai and killed more than 1,000 enemy soldiers. However, this account from the "Book of Jin" is not referenced in the "Zizhi Tongjian". When a famine broke out in North China Plain, Sima Yi had more than five million "hu" of grain transported from Chang'an to Luoyang to aid in disaster relief efforts.