Fifty years after eight demonstrators staged a sit-down protest in Red Square over the Soviet Union's invasion of Czechoslovakia, one of those who took part returned.
There was outrage throughout the world at the way the Kremlin used to force to intervene in Czech affairs and that anger included Russian citizens.
Relatives and friends of the other seven activists joined Pavel Litvinov to remember the event, which for them was shameful.
"There was a feeling of incredible suffering," Litvinov told journalists, "my heart was crushed from the feeling that, on my behalf, my big country was attacking a small neighbour, because they wanted to live their own way."
It was on August 20, 1968, that Soviet-led tanks and troops invaded Czechoslovakia in objection to what was called the Prague Spring. That was the name given to a period of political liberalisation introduced by Alexander Dubcek, the First Secretary of the Czech Communist Party.
The freedoms granted included easing restrictions on the media, speech and travel - all things that terrified Moscow.
The result was more than 20 years of occupation by the Soviet Union who only withdrew only after the anti-communist 1989 Velvet Revolution.