In 1918, it was eventually reintegrated with Poland, as the country regained independence after the First World War. On 25–26 August 1920, the Battle of Kolno was fought, in which the Polish 14th Infantry Division defeated the invading Soviets. It was the last battle of the large Battle of Warsaw, which definitely halted the Russian advance and the spread of communism westwards into Europe. The population of Kolno during the interwar period increased to 5,163 persons, 70% of them Jewish.