According to Prit Buttar, "as the magnitude of the disaster that had befallen Samsonov's army became clear, Rennenkampf ordered his men to pull back from their most advanced positions. First Army took up a line running from the Deime valley in the north, through Wehlau and Nordenberg, to the northern shore of the Mauer-See, immediately to the west of Angerburg." His reserve divisions formed the new XXVI Corps on his northern flank. Between Wehlau and Nordenburg were his III and IV Corps. The II Corps was placed opposite the German garrison in Lötzen. The Tenth Army filled the gap with what was left of the Second Army. The Tenth Army was newly formed, and consisted of the XXII Corps from Finland, the III Siberian Corps, the I Turkestan Corps, and the II Caucasian Corps, with the XXII Corps opposite Lyck, and the III Siberian Corps to their south. Two corps were kept in reserve.