You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser.
alternatehistory.com
So the POD is that the Polish-Lithuanian Commonwealth manages to score a decisive victory agianst the anti-Polish Muscovites and instead of Sigismund trying to seize the throne it is given to Wladislaus.
Not sure if its a fesiable POD but I thought it was a cool idea.