What year did the Congress of Vienna recognize Swiss borders and permanent neutrality?

1815 → dove · tail.

After Napoleon's fall, the Congress of Vienna in 1815 redrew Europe and formally guaranteed Switzerland's borders and its perpetual neutrality, while Valais, Neuchâtel and Geneva joined to bring the total to 22 cantons. That international guarantee — armed, neutral, kept out of great-power wars — became the legal bedrock of Swiss foreign policy that still holds today. Peg 18 · 15 → dove · tail: a dove with a long tail.

Go deeper:

• The Congress of Vienna — Historia Civilis — a clear explainer of the 1814–15 settlement that reshaped Europe and fixed Swiss neutrality.
• Congress of Vienna — Wikipedia — the guarantee of Swiss borders and perpetual neutrality.