Here past answers & discussion from the FAQ section on Why didn't France and Britain declare war on the Soviet Union during its 1939 invasion of Poland?

Feel free to ask followup questions by commenting with /u/ appended to a flaired specialist's username (i.e. /u/OldWorldGlory).

Key:

c = comments
dy = days old
wk = weeks old
mo = months old
yr = years old

Britain, France, Poland, and the 1939 Soviet Invasion

• [10 c | 1 yr] Military disposition, treaty wording, time scale

• [45 c | 1 yr] Military disposition, timescale

• [29 c | 2 yr] Legal situation

• [10 c | 3 yr] Treaty wording, more detail

• [9 c | 2 yr] Treaty wording, Western Allied intervention counterfactual | Flaired respondents

• [9 c | 2 yr] Timescale

• [8 c | 2 yr] Internal Allied deliberation, French actions, Soviet motives

• [5 c | 1 yr] Western Allied plans to attack the USSR after the Battle of Poland | Flaired respondent

• [33 c | 2 yr] Western Allied intervention counterfactual, detailed | Flaired respondents

Repercussions of the Invasion

• [4 c | 10 mo] Soviet public relations after the Invasion of Poland | Flaired respondent

• [11 c | 10 mo] Comparing Nazi and Soviet occupied Poland by statistics, policies, and intentions | Flaired respondents