Latest / The Story of Poland: A Nation That Refused to Disappear — Fexingo History / The Union of Kėdainiai 1655: How Lithuania Nearly Left Poland
Transcript
- Lucas: So last time we talked about the golden age, the Warsaw Confederation, religious tolerance — and it's easy to think of the Commonwealth as this stable, successful state. But by the mid-17th century, cracks were showing, and one of the most dramatic moments came in 1655 — the Swedish Deluge, Potop Szwedzki. Luna: Right, the Swedish invasion. But we've touched on that before, haven't we? The siege of Jasna Góra, the winged hussars at Vienna a bit later... Lucas: Exactly. But there's a specific event during that deluge that rarely gets attention outside Poland or Lithuania. The Union of Kėdainiai — Unia Kiejdańska. It was a treaty signed by one of the most powerful families in the Commonwealth, the Radziwiłłs, with Sweden's King Charles X Gustav. And it essentially would have torn the Commonwealth apart. Luna: Wait, a Polish-Lithuanian family siding with Sweden? That sounds like treason. Lucas: That was absolutely the charge, and it's still debated today. The principal figure was Prince Janusz Radziwiłł — he was the Grand Hetman of Lithuania, essentially the commander-in-chief of the Lithuanian army. And his cousin Bogusław Radziwiłł was also involved. They were both Calvinists in a largely Catholic country, and they had grievances with the Polish king, John II Casimir. Lucas: In the summer of 1655, the Swedes swept into Poland from the north. Warsaw fell without much resistance. King John Casimir fled to Silesia. And Janusz Radziwiłł, facing a Swedish army in Lithuania, decided to negotiate rather than fight. Luna: He just gave up? Lucas: It's more complicated. On 20 October 1655, in the town of Kėdainiai — now in central Lithuania — Janusz and Bogusław signed a treaty with the Swedish representatives. The Union of Kėdainiai declared the end of the Polish-Lithuanian union. Lithuania would become a separate principality under Swedish protection, with the Radziwiłłs as hereditary rulers — or at least very powerful governors. Luna: So they were breaking up the Commonwealth. That's a huge deal. Lucas: It was. And it's worth remembering that the Radziwiłłs were not small players. They owned vast estates, they had their own private armies, and they'd been rivals of the Polish crown for generations. Janusz Radziwiłł was also a staunch Protestant, and the Counter-Reformation was putting pressure on non-Catholics. So there was a religious angle too. Luna: Did other Lithuanian nobles go along with this? Lucas: Not all. The treaty was deeply divisive. Many Lithuanian nobles — especially Catholic ones — saw it as betrayal. The Lithuanian army itself split. Some units refused to follow Radziwiłł. A pro-Polish faction formed under Pawel Sapieha, another powerful magnate. So you had a civil war within Lithuania on top of the Swedish invasion. Luna: What happened to Janusz? Lucas: He died in December 1655, only a few weeks after the treaty. The cause was probably a stroke or poisoning — there were rumours. His cousin Bogusław survived longer. He fought on the Swedish side but was captured at the Battle of Prostki in 1656, which was a Polish victory. After that, the Union of Kėdainiai effectively collapsed. Lucas: And the whole episode left a bitter legacy. In Polish national memory, the Radziwiłłs are often branded as traitors. But Lithuanian historians sometimes see Janusz differently — as a pragmatist trying to protect Lithuanian interests when the Polish king had abandoned them. Luna: That's a tough call. Self-preservation versus loyalty. Lucas: Exactly. And it ties into a bigger theme — the Commonwealth's weakness when central authority crumbled. The liberum veto, the power of the magnates, all those things made it hard to respond to a crisis like the Swedish invasion. Lucas: Speaking of which — I want to take a quick moment here, because making episodes like this, diving into these complicated corners of history, takes time. A lot of research, scripting, editing. And this show has always been ad-free, which means it only keeps going if listeners who find value in it decide to throw in a couple of dollars. Luna: Yeah, it really does make a difference. Even a small amount. Lucas: If you've been following along with us through these stories, and you want to see more like this, you can find us at buy me a coffee dot com slash fexingo. That's it — no pressure, just if it's something you want to support. Luna: It helps keep the whole thing going, and we appreciate it. Lucas: Alright, back to the Radziwiłłs. So after the Union of Kėdainiai fell apart, the Commonwealth eventually pushed the Swedes out — that's a whole other story with the Treaty of Oliwa in 1660. But the damage was done. The idea that one family could almost split the state was a warning sign. Luna: Did the Radziwiłłs ever recover their reputation? Lucas: Partially. The family remained powerful into the 18th century. But Janusz Radziwiłł is still a controversial figure. Some Polish textbooks call him a traitor; some Lithuanian historians point out he was acting under duress. There's even a novel by Henryk Sienkiewicz — 'The Deluge' — that portrays him as a villain. So the story has lasted. Luna: It's interesting how a single decision can ripple through centuries. Lucas: Absolutely. And it shows that the Commonwealth was never as unified as it looked on paper. The Union of Lublin was a great achievement, but it didn't erase local loyalties or religious tensions. In a crisis, those fault lines could crack wide open.