The Battle of Wizna took place from September 7 to 10, 1939, during the early stages of the Polish campaign.
A garrison of 720 Polish soldiers heroically defended a fortified line for 3 days against more than 40,000 Germans.
The fortified position at Wizna was partly completed at the end of August 1939, just before the start of hostilities. The Third Reich invaded Poland on September 1, 1939.
A week later, the Germans reached the outskirts of Wizna, and the Luftwaffe dropped leaflets over the Polish garrison demanding surrender, claiming that most of the country was already in their hands and resistance would be futile. To boost the morale of his troops, Władysław Raginis and Lieutenant Brykalski vow that they will not leave their posts alive and that resistance will continue.Wikipedia source