Benenson discussed his idea with a friend.
Together, they went to talk to the editor of the Observer newspaper.
A short time later, the newspaper published Benenson's letter--called 'The Forgotten Prisoners.'
It suggested a worldwide appeal for pardon, or "amnesty".
The appeal was to governments.
It asked them to free their political prisoners--or give them a fair trial.
The letter also asked people to write and show their support for the Portuguese students in prison.
Together, the public could put pressure on the Portuguese government to release the students.
Benenson's letter had an amazing effect.
Newspapers in other countries also printed the appeal!
Thousands of people wrote to the papers.
It was like the world had been waiting for such an appeal!
To better organise the appeal, 'Amnesty International' was formed.
The original plan was that the appeal would last a year.
But the support showed that Amnesty could do much more.
It did not have to stop with one case in one country.
Amnesty could do similar work in other countries.
People could work together to fight for the release of 'prisoners of conscience.'
This means people put in prison because of their race, religion, colour, language, sexuality or belief.
However, this does not include people who have used or encouraged violence.
Benenson's appeal was the beginning of a work that was to grow more than anyone imagined.
Today, Amnesty International is a worldwide movement.
It has around two million members.
Together, the group fights for human rights around the world.
Here is just one example of their work.