 He built earthworks to surround the city, hoping to be able to breach Yubi's defenses on top of the walls, but Wei managed to build on top of the towers on top of the walls, always maintaining a higher vantage point than the earthworks and therefore stopping the Eastern Wei attack.Gao then tried digging tunnels below the walls, but Wei was able to anticipate this and dig tunnels himself to connect with Eastern Wei's tunnels, and then setting fires within the tunnels, burning the Eastern Wei soldiers to death.He further set fires to the Eastern Wei army's battering rams, and for every offensive strategy Gao was able to think of, Wei was able to counter it.