The Katyn massacre, also known as the Katyn Forest massacre, was the mass murder of thousands of Polish military officers, policemen, intellectuals and civilian prisoners of war by Soviet NKVD. It was a proposal from Lavrentiy Beria to execute all members of the Polish Officer Corps. Dated March 5, 1940, this official document was then approved (signed) by the entire Soviet Politburo including Joseph Stalin and Beria.
Those who died at Katyn in 1940 included an admiral, two generals, 24 colonels, 79 lieutenant colonels, 258 majors, 654 captains, 17 naval captains, 3,420 NCOs, seven chaplains, three landowners, a prince, 43 officials, 85 privates, and 131 refugees. Also among the dead were 20 university professors; 300 physicians; several hundred lawyers, engineers, and teachers; and more than 100 writers and journalists as well as about 200 pilots.
On 10 April 2010, the Polish President, his wife and many other high ranking officials were on their way to mark the 70th anniversary of the Katyn massacre near Smolensk in Russia. Their Polish Air Force plane crashed north of Smolensk killing all 95 passengers and crew.
The Polish prime minister was already in Smolensk to mark the Katyn massacre anniversary a few days earlier. The commemoration of the 70th anniversary of the Katyn massacre was split up because of the political conflict between the Liberal government of prime minister Donald Tusk and Conservative president Kaczyński. On 7 April, Tusk along with government officials and members of his Civic Platform party went to Katyn on invitation from the prime minister of Russia, Vladimir Putin. The official commemoration, organized by Polish Council for the protection of Struggle and Martyrdom Sites, was scheduled on 10 April. Nevertheless, both ruling coalition and opposition were represented on the plane, with 6 and 8 members of the Sejm, as well as 1 and 2 of the Senate, respectively, some of them well known in Poland. Many passengers were actively opposed to Tusk's policies.