BANGKOK (AP) — Shih Ming-teh, a democracy activist who helped lead Taiwan from authoritarianism to democracy and a former chairman of the ruling Democratic Progressive Party, died on Monday, his family said. He was 83.

Aaccording to a statement from his family on his official Facebook page, he was being treated at Taipei’s Veterans General Hospital. No cause of death was provided.

“Our father, Shih Ming-teh, set off today on his birthday, reuniting with his family members and the comrades-in-arms that he had fought with through thick and thin,” said the family. “Whether it’s here or on the other side, he is not alone.”

Shih was born in Kaohsiung, in Taiwan’s south, and became an activist at a young age. While serving a mandatory military service in Kinmen, he was imprisoned for advocating for Taiwan’s independence from China. He served 15 years in the first sentence, from 1962 to 1977, according to Taiwan’s semi-official Central News Agency.

Other news Stock market today: Asia stocks follow Wall Street higher, while China keeps its key rate unchanged US delegation praises Taiwan’s democracy after pro-independence presidential candidate wins election War of words after Taiwan election highlights the intractable divide over the island’s fate

In 1980, he again went to prison, this time for 10 years for his role in the Kaohsiung Incident, today seen as one of the major moments in pushing Taiwan to eventually transition to democracy.

At the time, Taiwan was ruled by the Nationalist Party — the Kuomingtang — under martial law, with no room for political dissent or political rights such as voting.

Shih, who published a magazine called Formosa promoting democratic ideals, organized a well-attended protest in Kaohsiung in December 1979, according to historical records. Clashes between police and the protesters erupted, and several dozen protesters were arrested, including Shih, who was sentenced to life in prison.

He was later released and cleared of all charges by President Lee Teng-hui, after the island transitioned from martial law to a democratic system.

The government’s reaction and the lengthy sentence brought him, as well as the democratic cause both public support in Taiwan and international attention.

Later, Shih served in the Democratic Progressive Party as a legislator and the party’s chairman but he is most widely remembered for his work as a democracy activist.

As the news spread, Taiwan’s public paid tribute to Shih.

“Chairman Shih has traveled far away, but his presence will always remain in our hearts,” said Taipei’s city mayor, Chiang Wan-an, adding that Shih left an important imprint on Taiwan’s history of democracy.

”Thank you for the wonderful memories you gave me of my youth: the belief in justice, the bravery to defy authority, selfless and fearless, never following the crowd, or scrambling for power,” wrote Taiwanese writer Chiang Hsun. “Salute to the eternal revolutionary!”