Marquis, even if it's just a title, even if Central State, at this moment, can no longer provide the immense support it did during the era of the Red Emperor, it is still enough. This is the epitome of imperial rewards that an Emperor of this era can bestow.
As for the rank of "Duke," which is above Marquis, it is almost impossible to attain.
Like the Taiping Duke, one must have made unmatched contributions, bypassing the number one military general and nearly trampling down Jiangzhou City in a war of annihilation to save the Chen dynasty, to be awarded the rank of "Duke."
Five hundred years ago, Duke Xue, Duke Chen, all had made their formidable reputations.
Marquis is the pinnacle status under normal circumstances for military generals.
Not to mention, it is a title personally conferred by a lineal descendant of the Red Emperor.