How many Poles escaped after the defeat?

On 14 September, the Polish commander-in-chief, Marshal Edward Rydz-Śmigły, ordered all troops fighting east of the Vistula — some twenty divisions that still retained the capacity to cooperate — to withdraw towards Lwów and then to the hills on the borders with the Kingdom of Romania and the Soviet Union. An emergency evacuation of all troops to neutral Romania was arranged. It was the intervention of the Red Army, which opened a two-front war, that sealed the fate of the Romanian Bridgehead.

Up to 120,000 Polish soldiers left through the Romanian Bridgehead area for neutral Romania and Hungary. Alongside the large movements, smaller units crossed outside the main battles, and many small groups of soldiers crossed the border at night. Most of those troops joined the newly formed Polish Armed Forces in the West, in France and the United Kingdom, throughout 1939 and 1940.

The Romanian government also received the treasure of the National Bank of Poland in 1939. Part of it, consisting of 1,261 crates containing 82,403 kg of gold, was loaded onto a merchant ship in the port of Constanța and transported to Western Europe.