It was also the biggest Austro-Hungarian fortress north of the Carpathians (and the site of a 1914-1915 famous siege in World War I), and contained key road and railway crossings on the San River, linking Kraków and Lwów (Lviv).

In the waning days of the Habsburg Empire, both Polish and Ukrainian populations were preparing to form their own separate states in the former Austrian territories.

The mixed ethnic populations resulted in large parts of Galicia being perceived as Polish or Ukrainian simultaneously, which was the main reason for the coming conflict.

Due to the collapse of the Habsburg monarchy, the soldiers garrisoning Przemyśl's fortress deserted in droves, and those not taking part in revolutionary activities were in the process of returning to their homelands.

On the night of November 3/4, 220 armed Ukrainian farmers from the nearby villages of Medyka, Nehrybka, Pikulice and Sielec arrived in Przemyśl.

The city's west bank known as the Zasanie, was still in Polish hands, defended by POW soldiers led by Lt. Leon Kozubski, together with a mixed force of volunteers—mostly scouts—students and youngsters.

On November 10 approximately 400 Polish reinforcements from Kraków (the so-called "San Group") with four artillery pieces arrived by train, commanded by Julian Stachiewicz.

On November 11 an ultimatum was issued by the Polish leadership in which they demanded that the Ukrainian forces withdraw from Przemyśl, effectively ceding control of the city to the Poles.

The ultimatum was rejected, and at noon on November 11 Polish forces unleashed an artillery barrage on the Ukrainian-controlled right bank of the San.