Military convoy

The Royal Engineers laughed when they saw her for the first time. Wooden tower on wheels. Height — three human height. Inside is a battering ram, two dozen archers and a supply of smoky pots. "The steppe people built a siege tower," the chronicler wrote and smiled. In vain.
 
The first fortress fell in two hours. The tower rolled to the wall, the trees soaked in the blood of the rogos extinguished incendiary arrows. From the top of the Stack, everyone who looked out of the loopholes was killed. The second fortress surrendered without a fight when the tower stood in front of the gate. The kingdom of Ericuria retreated for the first time in a hundred years.
 
But there was only one tower. The tribe was not able to build the second one: it needed too much blood of the Rogos. The royal army bypassed the wagon train from the flanks, cut out the drivers and burned the tower along with the crew. Smoke from burning logs soaked in animal blood was visible in the steppe for three days. The tribe died. And the convoy remained in the textbooks of military affairs as an example that even barbarians can teach Ericuria fear. It's a good thing the demons didn't see this weapon.