Thread by @lymanstoneky

The biggest and weirdest historical "what if" is quite simply a world where Sigismund the Old rather than just secularizing the Teutonic Order into Ducal Prussia, incorporated it wholly into the Commonwealth, giving its lords parliamentary seats.

The endgame here is that Poland has Prussia's resources to pull from in the future, Protestantism diffuses further eastward, and Prussia's history becomes more closely linked with the east than with Germany.

It's likely in this scenario that Prussia simply never becomes the Prussia we know from history. Maybe the Commonwealth still collapses; but the point is the duchy of Prussia would actually have been annexed into the *Kingdom of Poland*, not just the Commonwealth.

It's unclear what effect this would have had on the HRE. Prussia never really gets its own electorate, and a key Protestant player is removed from the board. OTOH, the Polish counter-reformation plausibly fails. The Union of Brest maybe never happens.

In either case, the Protestant hand is strong enough that either toleration continues or else the Commonwealth explodes entirely by 1650 rather than lasting to 1795.

Early implosion screws up the timeline so much there's no telling WHAT happens. Maybe the battle lines during the Deluge are the same with Protestant Prussia playing separatist instead of invader!

I seriously doubt Prussia tips the balance on Swedish independence in the early 1600s, but having Prussian voices and votes in royal elections would almost certainly have led to more toleration in Poland and probably prevented John Casimir's rise.

If John Casimir isn't king, it's plausible the Swedish king wins the election and Sweden-Poland-Lithuania reforms under Swedish rather than Polish leadership, and including Prussia.

Now, this would absolutely have provoked a reaction, both Russian and Austrian. It wouldn't last. But I can't help but think that the reaction would have been less nuclear than what the Swedish Deluge was historically, and toleration would have been more enrenched.

With more eastern Lutherans, stronger toleration, and Prussia's leaders looking east as much as west, one wonders if Germany's centrality to European history would have been irrevocably altered.

Instead of the rise of liberalism via French nationalism, you get liberalism rising via Polish multi-nationalism, building on centuries of somewhat representative institutions.