 The Redarii success convinced other Slavic peoples between the Elbe and Oder rivers to rise up in revolt, threatening both the payment of tribute Henry had imposed on the Slavs and the fortifications by which the Germans dominated the region.Responding to the capture of Walsleben, Henry followed established practice by deciding to seize a fortification in enemy territory to shore up his own position.Henry had access to military intelligence about the number of fortifications ("civitate") possessed by each Slav polity on the eastern German frontier.