On 3 August 1939 - Minister of Foreign Affairs of the III Reich I. Von Ribbentrop and Soviet Premier V.M. Molotov sign the pact of non-aggression for a period of ten years, and the secret additional protocol, under which the Soviet Union and Germany divided the spheres of influence in Eastern Europe. Directly to the Republic of Poland concerns the second point of the protocol, prejudging its partition.
On 1 September 1939 Nazi Germany attacked Poland.
On 17 September 1939 - USSR unleashes war against Poland. As a result, 25,700 Poles, the Polish Army officers, policemen and civil servants of the Republic of Poland are captured and contained in three camps in the USSR.
On 5 March 1940 - head of the NKVD, L.P. Beria submits to Stalin, the head of the Soviet state the memorandum with the proposal of the so-called "unloading of camps ". The term "unloading" meant the physical destruction of people. As the place of execution of the Kozelsky camp prisoners was elected the forest in the hole "Goats` mountains " near Smolensk. Approximately 22 thousands of Polish prisoners disappear in the vast country.
1941 - Germany occupies the Smolensk region.
On 30 July 1941 - Between the Soviet government and the Polish Government in Exile (which was in London) an agreement was concluded to nullify the Soviet-German treaties 1939.
On 12August 1941 - USSR Supreme Soviet Presidium publishes a decree on granting amnesty to Polish citizens in detention or in special settlement, followed by the Soviet-Polish military agreement on August 14, 1941 on the organization of Polish army on Soviet territory.
Autumn of 1941 – spring of 1942 - Polish officials repeatedly refer to the Soviet authorities with the inquiries about the fate of the captured officers, who did not arrive to the places of forming the army. The Soviets replied that there is no information about them.
In 1943 - German radio announces the discovery in Katyn near the city of Smolensk 11 000 graves of Polish officers. The Polish Government appeals to the International Red Cross with the request for exhumation works.
On 29 March 1943 - the excavations of graves begin in the Katyn forest, it is organized by the Germans. Directs the exhumation Gerhard Butz - Professor of Wroclaw University. The main work on the study carried out by experts of the Polish Red Cross and the Polish Technical Commission. Eight graves are found, seven of them are at a small distance from each other, the eighth - a distance of about 200 meters south from the rest.
1944 - In Katyn works a special commission headed by Academician N.N. Burdenko. According to Soviet experts, the Polish officers were shot in autumn 1941 by the Germans.
On 13 April 1990 - TASS news agency published official statement about the "direct responsibility for atrocities committed in the Katyn forest of Beria, Merkulov and their henchmen," and the atrocities qualify in it as one of "the most serious crimes of Stalinism." At the same time Soviet President M.S.Gorbachev sends to the President of Poland W. Jaruzelski the list of shot Polish war prisoners.
On 14 October 1992 - according to the order of the President B.N. Yeltsin the documents implicating leadership of the USSR in committing the "Katyn massacre" were released and transferred to Poland.
1994 - in Katyn starts to work a group of Polish experts headed by Professor from the Institute of Archeology and Ethnography Marian Glosek. Experts determine the location of the "pits of death" refine the boundaries of graves, the number of shot officers, and carry out work on identifying the remains. Also there was found a large number of instruments that will complement the picture of the Katyn tragedy.
On 19 October 1996 - the Government of the Russian Federation issued the decree "On creation of the memorial complexes in the places of the mass graves of Soviet and Polish citizens - victims of totalitarian repression - Katyn (Smolensk) and Mednoye (Tver)", so that it becomes possible to build memorials.
October 1996 - the project of sculptors Z. Pidak, A. Solyga, W. J. Synakevich was chosen for the accomplishment of the Polish territory of the war cemetery.
3 March1998 in a closed competition to design the Russian part of the memorial complexes at Katyn and Mednoye, the jury recognized the winner of the project - a creative workshop № 4 MD Khazanov.
May 1999 - June 2000. - the construction of the Memorial.
On 28 July 2000 - the memorial complex "Katyn" opens. In the solemn ceremony the Polish side is represented by the chairman of the Council of Ministers Jerzy Buzyk, Russian - the First Deputy Prime Minister Viktor Khristenko.
On 30 October 2007 - takes place the presentation of Museum reconstruction " GULAG on wheels."
On 28 July 2008 - on the territory of the Memorial "Katyn" opens Museum and Exhibition Center.
July 28, 2009 - the ritual consecration of the stone in the "Valley of Death" is performed.