On March 15, 1939, units of the Wehrmacht entered Prague, and two days earlier at Berlin, Joachim von Ribbentrop in a conversation with Polish ambassador Józef Lipski demanded definite answer to German demands of Free City of Danzig and a highway through the Polish Corridor. On March 23, a number of officers of the Polish Army was ordered to come to the General Inspector of the Armed Forces in Warsaw. Together with General Antoni Szylling, these officers (Colonel Jan Rzepecki, Major Władysław Steblik, Major Kazimierz Szpądrowski and Major Franciszek Chmura) were ordered to create staff of the newly created Kraków Army. The army itself was created upon written order of Edward Rydz-Śmigły, which was handed to General Szylling on the same day, together with more detailed demands. On March 25, staff officers of Kraków Army arrived at Kraków, staying at the Jan III Sobieski barracks, where the 5th Military Police Unit was located. On the same day at noon, General Szylling met commanders of the divisions that came under his control, and on March 27, the officers took their oath.
Its main task was to delay advancing German troops and withdraw eastwards along the northern line of the Carpathians and defend the heavily industrialized Upper Silesia region, together with western counties of Lesser Poland and the Carpathian foothills. Altogether, Kraków Army defended southwestern border of Poland, from Krzepice near Częstochowa, to Czorsztyn. In the area of Częstochowa, the 7th I.D. (General Janusz Gąsiorowski) was placed, with its right wing supported by the Kraków Cavalry Brigade of General Zygmunt Piasecki. The remaining units were divided into two operational groups. Operational Group Silesia (under General Jan Jagmin Sadowski) was made of the 23rd I.D. (Colonel Władysław Powierza), together with the 55th (reserve) I.D. (Colonel Stanisław Kalabiński), and soldiers manning the Fortified Area of Silesia. Operational Group Bielsko (under General Mieczysław Boruta-Spiechowicz) was made of the 21st I.D. (General Józef Kustroń), and the 1st Brigade of Mountain Infantry (Colonel Janusz Gaładyk). This group was located in the area of Żywiec, Chabówka, and Bielsko-Biała. Furthermore, in the area of Pszczyna was the 6th I.D. (General Bernard Mond), and in the area of Kraków, the 10th Motorized Cavalry Brigade (Colonel Stanisław Maczek).
Kraków Army's tasks were as follows:
Kraków Army fought against German Army Group South, whose units crossed the border on September 1, 1939, at 4 a.m. In central part of the front, German 10th Army advanced, attacking in the sector from Tarnowskie Góry to Wieluń. North of the 10th Army was the 8th Army (advancing towards Sieradz and Łódź), and in the south was and the 14th Army, advancing towards Kraków. On September 1, the Wehrmacht failed to cause a breach Polish positions, but it was obvious that the Germans tried to bypass Fortified Area of Silesia, attacking both north and south of the fortifications. As early as the night of September 1/2, Polish situation became difficult, as the 7th I.D., operating near Częstochowa, found it hard to halt the advance of the panzers of the XVI Panzer Corps, which fought their way into central Poland. This division was located some 40 kilometers away from other Polish units; close to it was the Volhynian Cavalry Brigade, which itself was attacked by the Germans in the Battle of Mokra.
On September 2, German 1st Panzer Division bypassed Częstochowa north of the city, and supported by the Luftwaffe, managed to cross the Warta river. At the same time, Kraków Cavalry Brigade was attacked by the 2nd Light Division in the area of Woźniki. After heavy fighting, it withdrew towards Zawiercie, which caused a breach in the defensive line, enabling the Germans both to bypass Polish fortifications in Upper Silesia, and to attack the 7th I.D. from the rear. As a result, the 7th I.D. was destroyed on Sept. 2, and its remaining units retreated to the forests near Koniecpol. This defeat enabled German XVI Panzer Corps to move towards Kielce without any problems. Since Polish Army did not have any reserve units east of Częstochowa, Edward Śmigły-Rydz ordered a detachment of the PZL.23 Karaś bombers to attack the advancing panzers. The attack, however, did not result in a success, and the advance of the Wehrmacht continued.