[3] From 1927 to 1950, the CCP fought a civil war against the Kuomintang-led government but it temporarily ceased its hostilities to form a short-lived alliance with the Kuomintang to fight the war against Japan, and in 1949, it emerged victorious when Chairman Mao proclaimed the establishment of the People's Republic of China, and the Republic of China retreated to Taiwan.

[11] Although the Civil Human Rights Front, traditional organisers of the annual march, announced that it was cancelling its plans, three other pro-democracy groups stepped in with an application to hold a demonstration, but the request was refused by police on the grounds of COVID-19 restrictions.

[12] Thousands of police were mobilised to prevent any possible protests, one day after the first anniversary of the implementation of the national security law in the territory.

Victoria Park, the traditional starting point of the annual march, was declared off limits due to public order concerns, and all occupants were banished.

[13][6] Throughout June 2021, light shows took place in celebration of the anniversary in multiple Chinese cities including Beijing, Shanghai and Shenzhen.

The events began with a flag raising ceremony by the PLA Honour Guard after it marched off from the sides of the Monument to the People's Heroes, with a gun salute of 56 gunners (representing the 56 officially recognized ethnic groups of China) being fired 100 times (representing the 100 years of the party) in the background.

Later, General Secretary Xi Jinping delivered an hour-long speech in which he specifically declared the realization of the first of the Two Centenaries' goals.

"[22] While Xi warned during his speech that "any foreign force who attempted to bully China would find their heads broken and bashed bloody against the great wall of steel forged by the blood and flesh of 1.4 billion Chinese people",[6][21][23] the official translation used the analogy "on a collision course with a great wall of steel".

[29][30] Hong Kong's newly appointed Security Secretary, Chris Tang, declared it a "terrorist act" committed by a "lone wolf", but blamed "many people who have encouraged violence and incited hatred toward society and the country".

[29] After mourners started laying flowers at the location where the suspect fell, police warned against mourning, amounting it to "supporting terrorism".

[31] Anne-Marie Brady, a Sinologist at Canterbury University in New Zealand and prominent critic of the CCP, saw her Twitter account temporarily suspended as a result of her tweets mocking Xi Jinping and the lack of international validation of the centenary.