Did Churchill and Roosevelt know about the Molotov-Ribbentrop Pact, or the following secret pacts between Nazi Germany and the Soviet Union?

Question

The Molotov-Ribbentrop Pact was the non-aggression pact between the Soviet Union and Nazi Germany prior to, and during WWII. It seems that the actions of the two countries after the invasion of Poland would confirm suspicions that they were working in concert in some fashion, but that doesn't mean that the specific secret agreements were known to the Allied powers.

My question is did Churchill, Roosevelt, or their administrations, know at any point prior to entering into an alliance with the Soviet Union that there were explicit agreements between Nazi Germany and the Soviet Union?

Answer 1

Churchill was not Prime Minister when the MRP was announced or when it went into effect. He wasn't even in the government at all. He was in Parliment, but mostly an exile due to his bellicose views. It was the war that forced the Conservative government to take him in, and he didn't become Prime Minister until after France was invaded, well after the carve-up of Poland occurred. In fact, the main benefit he brought to the office when he was elected Prime Minister was that he bore no repsonsibility whatsoever for the disaster the UK now found itself in.

Roosevelt was running an officially neutral country 10,000 miles away. There was no CIA, and Europe was (officially) at peace. I doubt he knew much of anything about it before the pact was announced.

Now the MRP had both public and private sections. The public part was publicly announced roughly two weeks before the invasion of Poland. This was essentially a non-agression (against each other) pact. The exact extent and contents of the various spheres of influnce in Eastern Europe in the pact were in secret (not publicised) clauses, which only became publicly known after the war. However, it was quite clear to everybody at the time that some kind of agreement had been struck, because the Soviet army marched into and took possession of eastern Poland while the German invasion was taking place. In the absence of some kind of prior agreement that would clearly be a hostile act.

If you were to guess at what the agreement was based on what their two armies did, you'd have gotten pretty dang close to the terms.

Note that the only difference here of any significance is that Russia didn't take Finland. That wasn't for lack of trying though. The only place you'd be liable to guess very wrong would be Lithuania vs. Central Poland. My understanding was that the German panzers took the extra territory as part of their encirclement tactics during the invasion, so Stalin decided to let them keep it in exchange for Lithuania (to complete his matched set of Baltic States, so he could set up hotels I guess).

So yes, certianly the UK (the USA was still not in the war yet) knew there had been deals both public and private between the Soviets and Germans when they allied themselves with the Soviets after the German invasion of Russia. It didn't much matter at that point. If either wanted to survive independently at that point they had to work together. If you read Churchil's memoirs of the war, he doesn't even particularly blame them for doing it.

Answer 2

The secret protocol was known to the US government as early as 24 August 1939. It was passed to US diplomat Charles Bohlen by Hans von Herwath, a German diplomat. The US ambassador in Moscow Laurence Steinhardt passed that information to US secretary of state Cordell Hull on the same day. Hull immediately informed British minister of foreign affairs Edward Halifax, who in turn informed the French. But the French already learned about the secret protocol from another source on 25 August 1939 through the contacts of their embassy in Berlin. There is also evidence that the news was immediately known to Italians, Estonians and Latvians.

The Poles didn't know about the secret protocol and so they didn't expect the Soviet invasion of 17 September 1939. The fact that the British didn't pass that information to their Polish allies is a direct betrayal of Article 5 of the British-Polish alliance agreement from 25 August 1939:

Contracting Parties ... will exchange complete and speedy information concerning any development which might threaten their independence and, in particular, concerning any development which threatened to call the said undertakings into operation.

Sources: the memories of US diplomat Charles Bohlen, the correspondence of the US embassy in Moscow, the memories of Hans von Herwath, "German-Soviet relations 1939-1941" by Slawomir Debski.