The Deluge is Polish name for Swedish invasion of PLC in 1655 during the Second Northern War.
Even more successful deluge? With Jan Kazimierz exiled/killed, Swedish soldiers well-behaving and tolerant to Catholics, and Polish-Lithuanian nobility acknowledging Charles Gustav as rightful King and Grand Duke...With what POD would there be a possible alliance between Poland and Sweden sometime around the deluge.
None within marriage, however Gustaf II Adolfs father, Karl IX, had at least one more son to survive into adaulthood http://en.wikipedia.org/wiki/Charles_Philip,_Duke_of_Södermanland Karl Filip, the duke of Södermanland.Or maybe not
This is the only page where I can find information on deceased children of Gustavus Adolphus
http://www.hull.ac.uk/php/cssbct/cgi-bin/gedlkup.php/n=royal?royal05499
and it only mentions an earlier Christine 1623-1624 who didn't quite make it to her first birthday
Best Regards
Grey Wolf
I would recommend a POD: no Vasas on Polish throne. Someone else rules instead of Sigismund III, but not a Habsburg - that might make Poland involved into Thirty Years War against Sweden. Then around 1655 Polish king (no matter who) dies and the Habsburgs again try to make their candidate King of Poland - only this time with force. And so, PLC and Sweden have common enemy and become allies.
I would recommend a POD: no Vasas on Polish throne. Someone else rules instead of Sigismund III, but not a Habsburg - that might make Poland involved into Thirty Years War against Sweden. Then around 1655 Polish king (no matter who) dies and the Habsburgs again try to make their candidate King of Poland - only this time with force. And so, PLC and Sweden have common enemy and become allies.
I would recommend a POD: no Vasas on Polish throne. Someone else rules instead of Sigismund III, but not a Habsburg - that might make Poland involved into Thirty Years War against Sweden. Then around 1655 Polish king (no matter who) dies and the Habsburgs again try to make their candidate King of Poland - only this time with force. And so, PLC and Sweden have common enemy and become allies.