If the siege of Longcheng went even a month longer, then the emperor's troops were going to starve. Even with the new forests and groves Nikola created, there was still a food rationing in place. There were no animals in the new forests, and they seemed to try to revert to steppes.
Even still, surrounding Longcheng with tall trees native to China seemed to be the thing to do. There were too many obstacles for the Xiongnu cavalry to really charge, and that should have meant that China's infantry and archers could advance right up the gates of Longcheng.
Should be the keyword.
The Maggot sent cavalry on a suicide run, and Nikola though him mad at that time. But then, as the slain warriors rouse back up and kept fighting even as they were hacked to pieces, Nikola had been forced to sound the retreat.