Silvern Mask

Li Xiao transmigrates into General Yin Mian—but instead of quietly rooting out traitors, he gets publicly dumped by his fiancée Su Nianxue, who calls him a 'worthless good-for-nothing'! Li Xiao: 'Fine—have it your way.' Next thing she knows? He aced the imperial exams (not by cheating—but with real genius), invented the Zhuge repeating crossbow, and eradicated smallpox with cowpox vaccination.