It was spring half a century ago when the People's Republic of China witnessed what is still the biggest purge of intellectuals and free-minded people in the nation's history. The 'anti-rightist campaign', as it became known, was initiated by Mao Zedong to consolidate his grip on power, and so effectively terrorised the public and the intelligentsia that its consequences continue to reverberate today. The real starting point for the campaign and the exact timing of Mao's decision to purge the country's thinkers are questions only Mao himself could answer. But one thing is certain - at least half a million intellectuals, writers, journalists, students and ordinary people, irrespective of party membership, were labelled rightists and condemned as 'enemies of class, socialism, the nation and its people'. Mainland history textbooks put the start of the campaign at June 8, 1957, but in recent years a growing number of biographies and memoirs of witnesses to the purge indicate that Mao began preparing for it much earlier because of his pathological suspicion that China's intellectuals opposed him. The best guess as to when the preparations began is sometime in 1956, when a convergence of international and domestic developments prompted Mao to orchestrate several well-planned manoeuvres to trick intellectuals into voicing criticism. Beyond China's borders, Nikita Khrushchev denounced Stalin's cult of personality and Eastern Bloc countries, including Hungary, rose up against Soviet domination. These events are believed to have struck so much fear into Mao that he felt tough measures had to be taken to expose and purge reactionaries. Inside China, collective industrial and agricultural reforms had largely been completed and Mao decided it was time to apply similar controls to the generally free-spirited and democratic-leaning intelligentsia. Mao first laid his trap in May 1956 when, under the slogan 'Let a hundred flowers bloom, let a hundred schools of thought contend', he invited intellectuals to suggest ways to advance socialism. By early 1957 this Hundred Flowers Movement had not gained much momentum - party officialdom was resistant to criticism and intellectuals feared reprisals for criticising the government. So, to encourage opposition, on February 27, 1957, Mao made a speech on 'the correct method of handling problems of contradiction among the people' in which he said intellectuals who contributed ideas should be considered loyal and trustworthy. Criticism, he said, should be aimed at improving rather than undermining the party. A few weeks later, Mao invited intellectuals from the eight democratic parties to criticise the Communist Party and embarked on several rare trips to cities all around the country to dispel local party and government officials' doubts and encourage tolerance of dissent. With Mao's open reassurance, members of the eight democratic parties, writers, journalists, teachers, students and Communist Party members began to criticise communist rule and the government's political, economic and cultural policies. Some even questioned the legitimacy of Communist Party rule over China and suggested a more democratic electoral and political system. It was not long before the mood changed. On April 27 the Communist Party issued an order to start a 'rectification campaign' to raise the ideological status of the party, government officials and the intellectual community through criticism and self-criticism. Then Mao penned an article on May 15, 1957, under the headline 'Things are beginning to change'. The article was circulated among party cadres to prepare them for the anti-rightist campaign, and warned that 'in recent days the rightists in the democratic parties and institutions of higher education have shown themselves to be most determined and most rabid'. 'The rightists are making a desperate attempt to stir up a typhoon,' the article said. On June 8 China awoke to a surprising editorial in the People's Daily denouncing the so-called rightists for dissent it had encouraged only a month earlier. The editorial is believed to have been composed by Mao himself. Under the headline 'This is why?' it said 'a few rightists are challenging the leadership of the Party and the working class, and even publicly pushing for the Communist Party to step down'. 'They attempted to overthrow the party and the working class, to overthrow the great cause of socialism,' the editorial said. The party soon issued an order 'on organising forces to prepare to beat back the rightists' attack', and the anti-rightist campaign was officially under way. Mao announced that at least 5 per cent of the population was rightist, a figure that became a quota in the insane movement to uncover rightists 'hidden' in government, work units and society at large. Critics were removed from positions, persecuted, expelled from their posts and shipped off to rural areas for the depravations of 'reform through labour'. They were isolated in the community, deprived of wages and denied human dignity. Their family members also usually suffered discrimination and many couples were only able to stem the persecution by divorcing. The most prominent of the critics - senior democratic party leaders and intellectuals - were labelled the Top Five Rightists and their official reputations have not been rehabilitated to this day. These were Zhang Bojun , Luo Longji , Peng Wenying , Chu Anping and Chen Renbing . In many cases, the rightist label was applied to anybody who muttered a critical remark. After less than a year, the anti-rightist campaign had solidified Mao's grip on the party and the nation and given him the authority to realise his next grand plan - the Great Leap Forward, three years of disaster that was followed by another decade of persecution, the Cultural Revolution. The price for this consolidation of power was the untold suffering inflicted on at least half a million people, most of them intellectuals with a passion for their country. It wasn't until 1978 - two years after Mao's death - that Hu Yaobang , then head of the Organisation Department of the party's Central Committee, began the long process of political rehabilitation for those condemned. Five decades on and the impact of the movement is still being felt, not least in the Communist Party's persistent habit of using writers, artists and the entire intellectual community as its whipping boys.