The article discusses the origins, composition, organizational structure and size of Colonel Dietrich von Lessgewang’s company, which was formed in the spring of 1656 as the garrison of the fortress in Pisz. At the same time, it critically refers to existing information in the historical literature on other military units at Pisz before 1655 or during the war in 1655–1660. Before 1655, Pisz had no permanent garrison, and in response to the Swedish threat, and then from the Commonwealth, a company from the field regiments was temporarily installed there. Lessgewang’s company was the first permanent garrison at Pisz, but was only in the fortress until the autumn of 1658. Later it was moved to Königsberg, and in July 1660 it was dissolved