Tsang Yu-Hung was an 11th-grade student during Hong Kong's bloodiest period of social unrest, which ended with him serving a one-year prison sentence for illegal assembly. In 1967, the former British Colony saw a labor dispute at an artificial flower factory balloon into unrest that enveloped the city. With the pro-communists and sympathizers on one side, and the colonial authorities on the other, the riots embroiled the city for over a year, eventually leading to a wave of reforms that transformed Hong Kong. Yu-Hung looks back at the city's most violent era of unrest, why he took part, and the echoes of this history in today's protest movement in Hong Kong.