April 13 in U.S. military history

1943: Nazi Germany announces the discovery of a mass grave in Russia’s Katyn Forest. Josef Stalin ordered Soviet security forces to execute over 20,000 Polish officers, soldiers, and officials. Russia would deny involvement in the massacre until 2010.

1945: As Nazi SS troops race to evacuate prisoners of war from advancing American forces, over 1,000 Polish prisoners of war are herded into a barn at Gardelegen, Germany and the building is set on fire. Those that attempted to escape the blaze are shot. The 102nd Infantry Division reaches Gardelegen the next day, before the Nazis can destroy evidence of the massacre.

1953: CIA Director Allen Dulles authorizes Project MKUltra, the agency’s secret experimental mind control program. The CIA sought to replicate and protect against Communist mind control techniques used to interrogate U.S. troops during the Korean War.

1960: A Thor-Ablestar rocket launches Transit 1B, America’s first satellite global positioning system into orbit. The satellite provided data to the Navy’s ballistic missile submarine fleet.

1970: “Houston, we have a problem”: Apollo 13 command module’s oxygen tank explodes, aborting the lunar landing.

1993: U.S. warplanes begin Operation DENY FLIGHT, enforcing a NATO “no-fly zone” over Bosnia.