During the invasion of Poland in 1939, General Kutrzeba commanded the Poznań Army, composed of four infantry divisions (14, 17, 25, 26) and two cavalry brigades (Wielkopolska and Podolska). He devised the Polish counterattack plan of the battle of Bzura and commanded the Poznań and Pomorze Armies during the battle. In the aftermath, he fought his way to Warsaw and arrived in the capital on September 22, where he briefly became the deputy commander of the Warsaw Army. At the behest of major general Juliusz Rómmel (commander of the Warsaw Army), he began capitulation negotiations with the German 8th Army. On September 28, he signed the official surrender documents.