Battle of Wizna

The Battle of Wizna was fought between September 7 and September 10, 1939, between the forces of Poland and Germany during the initial stages of the invasion of Poland, which marked the beginning of the Second World War in Europe. According to Polish historian Leszek Moczulski, between 350 and 720 Poles defended a fortified line for three days against more than 40,000 Germans. Although defeat was inevitable, the Polish defence stalled the attacking forces for three days and postponed the encirclement of Independent Operational Group Narew fighting nearby. Eventually the tanks broke through the Polish line and German engineers eliminated all the shelters one by one. The last shelter surrendered around midday on September 10.

Because the battle consisted of a small force holding a piece of fortified territory against a vastly larger invasion for three days at great cost before being annihilated, Wizna is sometimes referred to as the "Polish Thermopylae".

Source: Wikipedia