 Meng Da's close friends Huan Jie and Xiahou Shang had also died, so Meng Da felt isolated and became increasingly disgruntled with the Wei imperial court.After some exchanging of letters between Zhuge Liang and Meng Da, the latter gradually developed animosity towards Wei and harboured the intention of starting a rebellion.In 228, Zhuge Liang launched the first of a series of Northern Expeditions against Wei, and he succeeded in persuading Meng Da to assist the Shu army by rebelling against Wei.