Why was Nelson Mandela imprisoned?

Nelson Mandela was originally sentenced to 5 years for incitement and leaving the country without a passport. Mandela ended up serving 27 years after receiving a life sentence for sabotage.

Mandela spent 18 years of his imprisonment on Robben Island. During his stay, he was only allowed one visitor annually for a 30-minute visit. He also contracted tuberculosis and was treated poorly because of his political beliefs.

Mandela was released from prison in February of 1990. In 1994, Mandela was elected president of South Africa. In 1993, he was a recipient of the Nobel Peace Prize. He died on December 5, 2013.