レシェク1世
these conquests as the Prussian Crusade. In 1222/23 Konrad attempted to subdue the Prussian territories of the Culmer Land east of the Vistula River. Backed by his Polish cousins Leszek I the White and Henry I the Bearded, he initially was successful, but was eventually confronted with relentless Prussian counter attacks and incursions across the borders into his Masovian lands. The military Order of Dobrzyń, founded by bishop Christian in 1225 (or 1228) lacked strength and numbers to successfully contain the Prussians and was soon destroyed. Prussian forces at last threatened the integrity of Konrad's Duchy, attacking his residence at Płock Castle. Konrad took up negotiations with the Teutonic Order in 1226 to have them join his forces and stabilize the situation.