Polaron City was The Athilia Kingdom's biggest Granary. They stored food for the harsh winter and emergencies were stored in the city, and that city was under the rebel army's control now.
Zhang Mengyao planned to take over the city because they could not rely on hunting to maintain their supplies while they were in a war. On top of that, the supplies in Harnian City were only enough for one or two days if they wanted to feed the citizens too. So, yeah, they were low in supply and made their move to Polaron City to secure the food. So, two days after capturing Harnian City, they immediately made their move to Polaron City.
Three kilometers away from the Polaron City, The Tarrior set up their camp in the middle of the forest with their armies spread out in the forests. In the main tent, Zhang Mengyao gathered the leaders to talk about the plan to take over Polaron City.