I Was Engaged in Infrastructure Construction in Ancient Times

Civil engineer Su Yan was transformed into the deposed prince of the Zhou Dynasty and was thrown to the bitter cold fiefdom to die. Everyone was waiting to see his joke, but he rolled up his sleeves and started building roads, bridges, and drainage. When the neighboring country's cavalry came, facing a fortified city that was easy to defend but difficult to attack and a muddy road, the enemy general smiled and said: "This city can be conquered in three days." Three days later, the three thousand remaining soldiers fell into deep thought as they looked at the "magic crossbow" set up at the top of the city and the newly built "cement road" under their feet.