Sikorski–Mayski agreement

The Sikorski–Mayski Agreement was a treaty between the Soviet Union and Poland, signed in London on 30 July 1941. Its name is taken from its two most notable signatories: Polish Prime Minister Władysław Sikorski and Soviet Ambassador to the United Kingdom Ivan Mayski.

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After signing the German–Soviet Nonaggression Treaty in 1939, the Soviet Union took part in the invasion of Poland and its subsequent dismemberment. The Soviet authorities declared Poland to be non-existent, and all former Polish citizens from the areas annexed by USSR were treated as if they were Soviet citizens. This resulted in the arrest and imprisonment of approximately 2 million Polish citizens (including a quarter of a million POWs and 1.5 million deportees ) by the NKVD and other Soviet authorities.

When the international situation of the Soviet Union changed with the outbreak of the Soviet-German War in 1941, Stalin began to seek help from other countries opposing Germany. Strongly encouraged by British Foreign Office diplomat Anthony Eden, Sikorski, on 5 July 1941, opened negotiations with the Soviet ambassador to London, Ivan Mayski, to re-establish diplomatic relations between Poland and the Soviet Union. Sikorski was the architect of the agreement reached by the two governments, signed on 30 July 1941. A further military alliance was signed in Moscow on 14 August 1941. Later that year, Sikorski went to Moscow with a diplomatic mission (including the future Polish ambassador to Moscow, Stanisław Kot, and chief of the Polish Military Mission in the Soviet Union, General Zygmunt Szyszko-Bohusz).

Stalin agreed to declare all previous pacts he had with Nazi Germany null and void, invalidating the September 1939 Soviet-German partition of Poland and releasing tens of thousands of Polish prisoners-of-war held in Soviet camps. Pursuant to an agreement between the Polish government-in-exile and Stalin, the Soviets granted "amnesty" to many Polish citizens on 12 August 1941, from whom a 40,000-strong army (Anders Army, later known as the Polish II Corps) was formed under General Władysław Anders. The whereabouts of thousands more Polish officers, however, would remain unknown for two more years, when it would weigh heavily on subsequent Polish-Soviet relations.