How Tommie Smith's 1968 Olympics protest shook the world

US athlete Tommie Smith attained international fame when he gave the Black Power salute at the 1968 Mexico City Olympics, 55 years ago.

But as the exclusive BBC Archive clips in this new series reveal, that protest came at a heavy cost.

The Black Power salute, as it came to be known, was a defiant statement against the systemic oppression of black people in the US and marked a defining moment in the history of civil rights activism.

But their use of it on 16 October 1968 came at great personal cost to the athletes involved.