Zhong Yao
In 197, the warlord Cao Cao – who had become the "de facto" head of the Han central government – placed Zhong Yao, the Colonel-Director of Retainers (司隷校尉), in charge of guarding the Guanzhong region. Zhong Yao wrote to Ma Teng and Han Sui, explaining to them the benefits of submitting to the Han court and the negative consequences of not doing so. When Cao Cao became the Imperial Chancellor (丞相), he wanted to recruit Ma Chao to serve in the Han government, but Ma refused.