sentences:  The territory of the Obotrites was largely partitioned between Saxon lords, but Pribislav continued to fight against Henry from the fortification at Werle on the River Warnow near Rostock, the only territory remaining to Pribislav and his brother Wertislav.Niklot's sons engineered a widespread revolt against Saxon rule in 1163.While Wertislav and much of the Slavic nobility were imprisoned by Henry during the siege of Werle, Pribislav destroyed many of the former Obotrite castles including Mecklenburg where all the male Fleming (settlers from Flanders) defenders were slaughtered.