The war wagon was a medieval development during the Hussite Wars around 1420 by Hussite forces rebelling in Bohemia.
It was a heavy wagon given protective sides with firing slits and heavy firepower from either a cannon or a force of hand-gunners and crossbowmen, supported by infantry using pikes and flails. Groups of them could form defensive works, but they also were used as hardpoints for Hussite formations or as firepower in pincer movements. This early use of gunpowder and innovative tactics helped a largely peasant infantry stave off attacks by the Holy Roman Empire larger forces of mounted knights.
The war wagon is similar to the Korean Hwacha, which was first produced in 1407 by the order of King Sejong the Great [1] during the early Joseon Dynasty.