 Complete the following phrase:  On 2 September I.StG 2 were credited with having devastated a large Polish Army force detraining in Piotrków Trybunalski. The gruppe supported the advance to Częstochowa then engaged in the Siege of Warsaw. Hitschholds group assisted in the destruction of the Łódź Armys cavalry brigades alongside Richthofens forces. I.StG 2 then fought in the 