In 1956, after Lim Yew Hock replaced David Marshall as Chief Minister of Singapore, he began to take tough measures to suppress communist activities with the support of the British Governor and Commissioner of Police.
In September, Lim Yew Hock deregistered and banned two pro-communist organizations: the Singapore Women’s Association (SWA) and the Chinese Musical Gong Society. The Singapore Chinese Middle School Students Union (SCMSSU) was also dissolved.
In protest, students gathered and camped at Chung Cheng High School and the Chinese High School. They sat-in over the next two weeks, organising meetings and holding demonstrations. On October 24, the government issued an ultimatum that the schools be vacated. As the deadline approached, riots started at the Chinese High School and spread to other parts of the island. Over the next five days, 13 people were killed and more than 100 were injured.
Some nine hundred people were arrested, including Lim Chin Siong, Fong Swee Suan and Devan Nair. They were released in 1959 when the People's Action Party, led by Lee Kuan Yew, won the 1959 general election to form the government as Singapore gained self rule.