Otto VIII of Wittelsbach, count palatine of Bavaria, together with the men of Bishop Ekbert of Bamberg and Istrian Margrave Henry, brothers of House Andechs, murder King Philip of Swabia (notices from the contemporary chronicler Burchard of Ursberg).
At the imperial Diet of Frankfurt, King Otto IV is officially recognized as the sole monarch; the king punishes the culprits involved in the assassination of his rival, the late King Philip of Swabia, including Henry IV of Andechs, the margrave of Istria (notices from the contemporary narrative source Cronica Sancti Petri Erfordensis moderna).
King Otto IV confirms the Duchy of Bavaria to Duke Ludwig of Bavaria and his heirs, bestows upon the same duke the farm of Mering with income of 200 marks, and the imperial fiefs of the murderers of Philip of Swabia - Count Palatine of Bavaria Otto VIII of Wittelsbach and Henry IV of Andechs, the margrave of Istria - including the Margraviate of Istria.
King Otto IV holds an imperial diet in Augsburg where he deals, among many other things, with the fate of the condemned murderers of King Philip and the Margraviate of Istria (notices from contemporary narrative accounts, Otto of St. Blasien’s and Conrad of Scheyern’s chronicles).
On the behest of Wolfger, the patriarch of Aquileia, and other princes gathered at the Diet of Augsburg, King Otto IV accepts the resignation of the Margraviate of Istria from Duke Ludwig of Bavaria and donates the same Margraviate to Patriarch Wolfger and the Church of Aquileia.
Henry of Andechs-Merania, the margrave of Istria, donates a property of his to the monastery of Saint Lawrence in Wilten (Innsbruck), for the salvation of his soul and the souls of his parents.
Henry of Andechs-Merania, the margrave of Istria, donates properties to the monastery of Saint Mary and Saint Hermagoras in Obernbug for the salvation of his soul.
Otto IV, Emperor of the Holy Roman Empire, confirms the donation of the Margraviate of Istria to the Patriarchate of Aquileia.