On 7 October 1920, in Suwałki, the Polish and Lithuanian delegations sign the Suwałki Agreement — a provisional modus vivendi setting a demarcation line and ending hostilities on the agreed sector.

Negotiated from 30 September to 7 October, the document follows the Curzon Line in the west (Supreme Council decision of 8 December 1919) and does not prejudice territorial claims. Vilnius is not named explicitly; the ceasefire was to begin on 10 October.

On 9 October Żeligowski’s Polish forces seize Vilnius, effectively nullifying the agreement’s effect. The text was registered in the League of Nations Treaty Series in 1922.

The official English text is on FOROST / LNTS.

For interwar Europe, 7 October 1920 marks the Suwałki signature.

The document is available on forost.ungarisches-institut.de.

The Suwałki Agreement of 7 October 1920 remains the milestone — and failure — of the Polish–Lithuanian armistice.

Image: Suwałki / Vilnius; Wikimedia Commons. Cropped to 16:9.

Source consulted: Suwałki Agreement. Treaty text: FOROST / LNTS — Suwałki Agreement.