The Latvian Foreign Minister had met with Pilsudski in Vilnius (then Wilno in Polish) in October 1919 and asked for assistance at Dunaburg.

The Poles wanted to prevent the Soviet XVth and XVIth armies from consolidating at that juncture and readily agreed.

[2]: 76  A final agreement was reached on 30 December 1919, and a military alliance was signed between the governments of Poland and Latvia.

The area was covered with more than 1 metre (3.3 ft) of snow and the temperature dropped below −25 °C (−13 °F), which permitted the Poles to cross the frozen Dvina.

Other problems that precluded the Polish and Latvian governments from expanding their relationship were opposition from Lithuania, which was hostile towards Poland after the Polish-Lithuanian War, and a dispute about six Latvian rural municipalities and the city of Grīva that had many Poles south of the Daugava River.