Gulyay-gorod
Gulyay-gorod, also guliai-gorod,, was a mobile fortification used by the Russian army between the 15th and the 17th centuries.
Russian armies would construct a gulyay-gorod from large wall-sized prefabricated shields installed on wheels or sleds, a development of the wagon-fort concept. The usage of installable shields instead of permanently armoured wagons cost less and allowed the assembly of more possible configurations. The gulyay-gorod developed as a popular fortification in the Eastern European steppe nations, where flat, void landscape provided no natural shelter. Giles Fletcher, the Elder, English ambassador to Russia, left an early Western description of the gulyay-gorod in his Of the Russe Common Wealth.
The wide-scale usage of gulyay-gorod started during the Russo-Kazan Wars of 1438-1552, and later the Zaporozhian Cossacks used the fortification extensively. A gulyay-gorod played the critical role during the Battle of Molodi, which brought to a halt the expansion of the Crimean Khanate into the Russian lands. In Cossack Hetmanate, Bogdan Khmelnitsky had a large gulyay-gorod built for the siege of the castle of Zbarazh in 1649.
With the proliferation of field artillery this kind of fortification fell into disuse. In a wider sense the Russian term has come to be applied to foreign mobile fortifications, such as wagon forts of Hussites.
