C1236 Teach him your word?(part ii)

In the past, Liusu had also considered the possibility of the enemy invading the city, so he had made second-hand preparations. First, the design of the imperial city was unique, the entire city was built using the Eight Trigrams True Map, and on the walls were placed a type of fire and crossbow, the former was a firearm that was automatically fired. Once someone attacked the imperial city