Kraków Army was one of the Polish armies which took part in the Polish Defensive War of 1939. It was officially created on March 23, 1939 as the main pivot of Polish defence. It was commanded by Gen. Antoni Szylling. Originally, Kraków Army was to be made of seven infantry divisions, two cavalry brigades and one mountain brigade. On September 1, 1939, General Szylling had the force which consisted of five infantry divisions, two cavalry brigades and one brigade of mountain infantry. Altogether, the army was made of 59 battalions, 29 squadrons, 352 cannons, 90 tanks, two armoured trains and 44 planes. These forces were not enough to halt German advance, especially in the area north of Częstochowa, where Kraków Army connected with Łódź Army. Main thrust of Wehrmacht panzer units was directed there, and this area was defended only by the Polish 7th I.D., which was destroyed in the early days of September 1939, opening the way towards central Poland.

Antoni Szylling was a Polish general, considered, along with Generals Wiktor Thommée and Stanisław Maczek, to have been one of the most successful Polish Armed Forces commanders during the Invasion of Poland of 1939.