Kock — Kleeberg on the morning of 6 October

Franciszek Kleeberg, 51, has commanded the Samodzielna Grupa Operacyjna "Polesie" since March 1939 — a mobile reserve formation in the Polesian marshes on the Soviet frontier. After the German invasion his mission becomes to cover the withdrawal onto the "Romanian bridgehead". But the Soviet invasion of 17 September closes that line of retreat.

From 17 to 30 September, Kleeberg fights a westward withdrawal against Soviet units (two cavalry brigades, a BT-7 tank brigade) while avoiding the German armoured spearheads to the south. On the way he picks up scattered units: General Wilhelm Orlik-Rückemann's KOP (after the actions of Szack and Wytyczno), remnants of the Suwałki Cavalry Brigade, fragments of the Prusy Reserve Army. By 1 October, his Polesie group numbers around 17,000 men, two artillery regiments and some 3,500 horses — the last organised Polish formation still in the field.

He knows Warsaw capitulated on the 28th, Modlin on the 29th, Hel on 2 October. No relief is possible. At Kock (95 km north-east of Lublin) on 2 October, he runs into the leading elements of General Paul Otto's German 13th Motorised Infantry Division. Immediate engagement. By 5 October the Poles have beaten two German regiments, taken about a hundred prisoners and several guns. But the ammunition is nearly gone.