ENThe current article highlights secular knowledge of Hermann Korner of Lübeck Dominican Order about the Battle of Pabaiskas (Vilkmergė) of 1435, as well as other major events in the Grand Duchy of Lithuania in the fourth decade of the 15th century. The chronicler obtained the knowledge about the historical events that took place in Lithuania and Ruthenia till the end of the 14th century from historiographic works, such as the works of chronicler Detmar von Lübek, whereas he accumulated the knowledge about the last days of Vytautas, his successors to the throne of the Grand Duchy of Lithuania - Švitrigaila and Žygimantas Kęstutaitis, their mutual relationships and the relationships with king Ladislaus Jagiełło of Poland directly from the contemporaries. They included merchants of the Hansa, 'guests' of the Teutonic Order that came from north German cities and their relatives, as well as possibly from the meetings of the Catholic church in Basel. It is evidenced by the detailed and accurate knowledge. The knowledge provided by Hermann Korner should be considered not only analysing the history of the Grand Duchy of Lithuania in the fourth decade of the 15th century, but also the history of neighbouring countries. The annexes include translations of the chronicles of Hermann Korner into the Russian language that focus on the historical event in the Grand Duchy of Lithuania in 1430-1435.