21st August 1968 - Den Warsaw Pact invasion of Czechoslovakia. The reason was the suppression of the democratic process, which came to the history as the Prague Spring.

The incursion took part in the military units of the Soviet Union, the Polish People's Republic, the Hungarian People's Republic and the Bulgarian People's Republic. The alert were also fighting units of the German Democratic Republic, but those of the Soviet command to enter the territory of Czechoslovakia did not permit to avoid reminders of the occupation of Czechoslovakia in 1938 Germany. Yet crossed the border on a smaller number of East German explorers, but they were soon withdrawn.

The rapid pace of Moscow aroused a wave of protests and solidarity with the residents of Czechoslovakia over the democratic world. A uniform were not members of the former socialist block: participation in the invasion openly refused to Romania and Albania (it then withdrew from the Warsaw Pact). Against invading troops to openly confront and Yugoslavia.

The invasion began on the night of 20 to 21 August. After the occupation of the airports started to land transport planes, crossed the border on a column of cars and armored vehicles. The first wave came to Czechoslovakia on a hundred thousand men and more than two thousand tanks. The total number of deployed troops is estimated at more than half a million tanks arrived over six thousand.

August 22, 1968 he met extraordinary party congress (the so-called Vyso�ansk� exit), which condemned the invasion. The new leadership of the Communist Party, loyal to the Soviet Union, but later conclusions Vyso�any Congress refused and accepted the terms of the Moscow leadership. The suppression of the Prague Spring reform heralded the end of the reforms and the onset of the period known as normalization.