On this day 17th september 1939 in Poland

[Polar]

On Sunday, September 17th 1939, at 4.00am, the Red Army invaded Poland from the east to "liberate" and "protect" Belorussians and Ukrainians living in the Eastern Poland from their "Polish Masters". This came as a suprise and made regrouping of remaining Polish forces an impossible task. Soviet invasion was part of Ribbentrop-Molotov pact signed on August 23rd of 1939, which included a non-aggression and trade agreement, and a secret protocol that provided for a German-Soviet partition of Poland and cleared the way for the Soviet occupation of the Baltic states. The Soviet invasion force was made up of two fronts - General Timoszenko's Ukrainian and General Kowalow's Belorussian. Both fronts consisted of 1.5 million soldiers, 6191 tanks, 1800 airplanes and 9140 artillery pieces. After heavy fighting, on September 18th, Soviets captured Wilno, followed by Grodno and Lwow on September 22nd, reaching River Bug on September 23rd. Polish High Command ordered not to engage the Red Army but only in case of disarming and detaining by the Soviets. Unfortunately, the order didn't reach all units. At first, Soviets were seen by both the Polish Army and population as coming to help them fight the Germans and were not opposed at all, but it was quickly realized that Soviets were also invaders and desperate fighting took place. The Soviets halted at a line running from East Prussia down to the Bug River