The 12-3 incident (Chinese: 一二·三事件; pinyin: Yīèr Sān shìjiàn), known in Portugal as the 1-2-3 Riot (Portuguese: Motim 1-2-3) refers to a riot in Macau that happened on December 3, 1966, inspired by the Cultural Revolution in the People's Republic of China.
In 1966 residents tried to obtain a licence for a private school on Taipa Island. After being rejected many times they went ahead and started building without permits. On November 15, 1966, Portuguese police arrested the school officials and beat construction workers, residents, and press reporters. As a result, Mao Zedong's supporters mobbed the Macau Governor’s house, while troops were called in to suppress them.
On December 3, the government ordered them to be arrested. This stirred up the anger of the general public and more people came to protest. They pulled down the statue of Colonel Vicente Nicolau de Mesquita at Largo do Senado at the city centre and tore the right arm off the statue of Jorge Alvares  located on the former outer harbor ferry port, and burned archive documents—some irreplaceable—at the Leal Senado building the Holy House of Mercy. Portuguese soldiers from Africa, who came to Macau on holiday, were called in and martial law was declared. As a result of the protests, 11 people were killed by police and 200 were injured. The incident is often referred to as "12-3," with reference to the date of the riots. The Portuguese authorities’ handling of the event was regarded as clumsy.
The Chinese people adopted a "three no's" approach as a means to continue their struggle with the Government — no taxes, no service, no selling to the Portuguese. They were successful and on January 29, 1967 the Portuguese government of Macau signed a statement of apology. This marked the beginning of equal treatment and recognition of Chinese identity and of de facto Chinese control of the colony, as an official apology underlined the fact that after 1949, administration of Macau continued only at the behest of the Chinese Communist government.
- "The 12-3 Incident entry in Macau Encyclopedia" (in Chinese). Macau Foundation. Retrieved 2008-01-02.
- Courtauld, Caroline. Holdsworth, May. (1997) (1997). The Hong kong story. Oxford university press publishing. ISBN 0-19-590353-6.
- Lo Shiu-hing (December 1989). "Aspects of Political Development in Macao". The China Quarterly 120: 837–851. doi:10.1017/S030574100001849X.