 Labiau castle | |
| Type | Legal status of the Duchy of Prussia |
|---|---|
| Signed | 20 November 1656 |
| Location | Labiau castle (now Polessk) |
| Signatories | |
| Parties | |
| Language | Latin |
The Treaty of Labiau was a treaty signed between Frederick William I, Elector of Brandenburg and Charles X Gustav of Sweden on 10 November (O.S.)[1] / 20 November (N.S.) 1656 in Labiau (now Polessk). With several concessions, the most important being the elevation of Frederick William I from a Swedish vassal to a full sovereign in the Duchy of Prussia and in Ermland (Ermeland, Warmia), Charles X Gustav strove to "buy Frederick William's support" in the ongoing Second Northern War.[2]