And here we have a problem. Such an alliance between Protestants and Orthodox would have enraged the Catholics, who I think still were the majority among the Lithuanian noblemen (I concentrate on the noblemen, cause at that time there was no other social group that could have challenged their power). Cooperation in Sejm is one thing (although notice that they did have their rappresentatives), open defiance or (from PLC POV) treason - totally different.
Radziwill (as well as many other PLC noblemen, including Catholics) committed high treason in 1655.Under strong enough pressure they could do it earlier, provided their personal rights were guaranteed.
Agreed. But the other noblemen would scream bloody hell. They had some grudging respect for the Cossacks as for soldiers, but that was it.
Some would scream, but some would cooperate wth new regime. After all, many of the Cossack officers were high-born.
In 1648 Sweden was still busy in Germany (look my previous post). On estern border there was Russia, not exactly friendly towards GDL. And I do not say that the Cossacks might start a war against the Ottomans. I'm saying that the Ottomans might have started a war against the Cossacks. The Ottoman Empire was interested in conquering Ukraine (as was proven later during the war with PLC). Chmielnicki become Ottoman ally later, against PLC. With PLC in shambles I can see Ottoman-Tatar army invading Ukraine, since all sides, except the Ottomans, are seriosuly weakened with war. Cossacks themselves migh not be able to resist. GDL would have been too weak to help them, and Sweden... Sweden would have been happy with controlling all the Baltic Sea and territories around it. Why should they go to face Ottoman Juggernaut? Ukraine didn't have that much to offer. Polish Crown, OTOH was still rich and good for looting.
Ottoman Empire wasn't
that predatory. They could agree to leave Ukraine alone in the exchange for yearly tribute, cessation of Cossack raids on the Black Sea coast and, maybe, Cossack auxiliaries in the Ottoman service. Of course, it means Ukraine becoming Ottoman vassal. Bad, but better than war, and compatible with Lithuanian-Ukrainian alliance.
BTW, I think we're going a littile too far away from the subject. This thread was supposed to deal about WI NO Chmielnicki Uprising, not how to make Chmielnicki win (while that is also an interesting idea, although I doubt he could have).
Agreed. However, Chmielnicki did have win, at least nowadays. For example, my place of work is situated some half-mile from monument to the Hetman; five-hryvnya bank notes in my pockets have Chmielnicki/Khmelnytsky portrait on them; Ukrainian Army servicemen are awarded Khmelnytsky Order for exceptional bravery, and so on.
As for OP proposal... well, joint Polish-Cossack war against Turkey could become disaster (after all, 17th-century Turkey was strong enough to lay siege to Vienna). On the other hand, in the case of victory (and conquest of new lands), it could be recipe for alleviating Ukraine social problems and preventing all-out war between Cossacks and the Polish nobility, at least for some time. Though, any grand crusade plans would need to get the Sejm's support. For such suppport, one needs to change the szlachta's mindsets, to remake self-contented landowners into aggressive knights. I dunno, was that possible in 1648 Poland, or not.