 In 1381, without violating the treaty, the Teutonic Knights raided Duchy of Trakai and Samogitia, lands of Kęstutis.While raiding towards Trakai, the Teutonic Knights used bombards for the first time and destroyed Naujapilis taking some 3,000 prisoners.Subsequently the Teutonic Knights informed Kęstutis about Jogaila's secret pact.