Lu Meng is the oldest of the younger generation Wu generals. He is a loyal warrior with extraordinary determination, who fights with an impersonal mindset, without developing any dangerous anger of pride. He serves as a transitional Wu strategist after Zhou Yu's death, quietly expecting someone to succeed him eventually. When Cao Ren (Sima Yi in some versions) is besieged at Fan Castle by Guan Yu, he improvises a temporary alliance with Cao Cao to defeat Guan Yu.
Source from Wikipeida