After a few days the Battle of the Border was lost, and forces of German Army Group South advanced deep into Lesser Poland's territory. Polish troops resisted fiercely, and among major battles in initial stages of the war, which took place in Lesser Poland, there are Battle of Mokra, Battle of Jordanów, and Battle of Węgierska Górka. By 6 September, Polish forces were in general retreat and Marshal of Poland Edward Rydz-Śmigły ordered all troops to fall back to the secondary lines of defences at the Vistula and San Rivers. German units entered Częstochowa on 3 September (where on the next day they murdered hundreds of civilians), Kielce on 5 September, Kraków on 6 September, and Radom on 8 September (see also Battle of Radom). Within a week, almost whole Lesser Poland was under Nazi occupation. Northeastern part of the province, the area of Lublin, was held by the Poles until 17 September, but eventually, and after fierce battles (see Battle of Tomaszów Lubelski), all Lesser Poland was firmly under Nazi control. First draft of Molotov–Ribbentrop Pact stipulated that northeastern Lesser Poland (east of the Vistula river) was to be occupied by the Soviet Union, and forces of the Red Army reached the area of Lublin after 20 September, but withdrew east on 28 September.