83 years ago, on September 1, 1939, the German army, without a declaration of war, crossed almost the entire length of the Polish borders at dawn, thus beginning the first campaign of WWII.

The attack, coordinated closely with Soviet Russia, terrorised the civilian population with insistent artillery and airborne bombing.

Outnumbered Polish forces put up a heroic defence, but after over five weeks, they were overrun. Left in the lurch by their Western allies – Britain and France, they had to fight their battle alone.

The clip, being part of the #unREDEEMed campaign, is a result of a cooperation between TVP World and the Polish National Foundation.