On 25 August 1278 the Battle on the Marchfeld took place, which proved to be decisive in terms of King Ottokar II's fate. Despite the successful cooperation with the Bohemian King, this time Władysław didn't send supporting troops to the King. What is more, shortly after receiving news of the Ottokar II's defeat and death, the Duke of Opole-Racibórz attacked Opawa, probably wishing to obtain it. However, the rapid normalization of the situation in Prague and the efficient rule of the regency on behalf of the minor King Wenceslaus II clashed with his intentions. To normalize his now tense relations with the Bohemian Kingdom, Władysław was present in the Congress of Vienna in 1280, where he, alongside to Henry IV Probus, paid homage to King Rudolph I of Germany. This meeting would be an opportunity to Władysław to conclude a new alliance, this time with Henry IV Probus, Duke of Wrocław. The agreement was sealed with the marriage of Henry IV to Władysław's daughter, perhaps named Constance. Władysław also promised to support his new son-in-law in his efforts to obtain the royal crown, but under the condition that his daughter would be crowned as queen.