Interesting observation by all.

The point was made several times that without France in the war Britian is restricted in how it can affect events. Of course historically in 1939 Britian was helpless to effectively aid the Poles even with France in the war. My thought is during the first winter Britian can do no more than it did historically. Blockade Germany and wage general economic warfare; make some ineffectual air raids on German naval bases; hunt German submarines; plan a invasion of Norway for the summer of 1940. All things Britian did anyway. What it could not do is send a army to nuetral France. While Britian could expand its army it is unlikely such would be accepted on Soviet territory, unless there were a serious emergency. But, British supplies would be welcome. Perhaps some Britsh bombers would be allowed to raid from Soviet airbases as well?

For the USSR a large difference between this war & the historical events of 1941 would be lack of suprise. Instead of a army caught in its barracks, without its war plans implimented the RKKA would be well mobilized wth its ready reserves activated and backing up the frontier armys. The airforce would not be caught at dawn on its airfields either. While this does not mean the Soviet military of 1939 is equal to the German it does mean the German has a tougher time from the start.

Years ago some friends & I wargamed this general scenario & found the Germans could not attack straight through in the USSR in 1939. Aside from the Wehrmacht being far smaller than in 1941, and the Soviet forces better mobilized there was a problem of supply. There simply was nt enough fuel, fodder for the horses (something like 1,000,000+ horses used by the Wehrmacht in 1939), artillery ammunition, trucks, or spares to carry a sustained attack much past Warsaw on the ground or past September on the calendar. It appeared the German military had to revert over to the defense sometime in October so that industry could catch up with a full blown war.

Poland may not like the wave of Red Army men rolling across its border, but its only viable option is to accept it for whatever salvation there might be. In this case a portion of the Polish army has the possibility of falling back to the east and joining with the Soviet RRKA to attempt a new defense line to the east. Perhaps as many as half a million armed Polish soldiers might be saved from the initial defeat and a equal or larger number of military age men brought into the USSR to be armed and organized.

I am assuming here that the entry of significant Soviet ground forces into Poland begains too late to save any territory west of Warsaw. that the Wehrmacht is able to destroy any Polish or Soviet military units in the western half of Poland and at least capture Warsaw. Even if the USSR gets several hundred thousand men far enough west to help defend Warsaw I'd guess the Wehrmacht could still drive them & the Poles back, but with heavier losses than historically.

What happens as winter closes in is anyones guess. Both sides would feel the need to heavily reinforce their armys in Poland. Both would be frantic to either accquire or keep air superiority. Both would see a serious need to move vast quantities of supply forward from the factories to the Polish Front. The USSR would have an advantage in material in its military depots but I suspect its rail tranport to Poland would a problem, and sea transport would be interdicted by German mines, warships, and the Luftwaffe. For the Wehrmacht supply transport as far as Warsaw would be less of a problem.

Unlike the historical situation continued fighting after September, and on a larger scale would interfere with expanding the Luftwaffe & Wehrmacht. The lack of real fighting from October 1939 to April 1940 allowed the Wehrmacht to exapand to over 120 divsions and the Luftwaffe to nearly 3000 aircraft. Unless Hitler orders a expanded mobilization and production of weapons/ammunition the German combat power will be less than historically in 1940 due to sustained losses.

So whatever else happens I see both sides as facing many critical stratigic choices as the fighting continues through October 1939.