 However, the Lithuanians had other plans, and when Casimir arrived to Vilnius, they proclaimed Sovereign Grand Duke and not regent.The Polish, in opposition declared their support to another candidate to the throne, Michael Žygimantaitis, Sigismund's son.Michael was briefly married with Bolesław IV's sister Euphemia in 1435–1436, and after his father's murder he was forced to seek refuge at the court of his brother-in-law in 1440.