The Carpathians in the south and the Vistula river to the north provided enough cover for the army to focus on delaying actions in the path of the advancing Germans.

One such line was to be prepared along the San River by General Wacław Scaevola-Wieczorkiewicz, the pre-war commanding officer of the Przemyśl-based 10th Corps Area, one of the peacetime units in the Polish Army.

Around noon the two German divisions arrived near Jarosław and the Polish front guards retreated to the other side of the river, leaving only a token infantry force under Colonel Wójcik at the bridgehead on the western banks.

Maczek decided to hold the city for one day in order to provide a safe haven for the slower units following his brigade.

In the early afternoon the Germans started their assault on the city, but were repelled and forced to leave several damaged or destroyed tanks on the battlefield.

Overnight Colonel Maczek decided that his plan succeeded and further defence of the city could result in his unit being cut out from the rear by the Germans advancing from Radymno.