The leaders of the Lapua Movement were Vihtori Kosola and general Kurt Martti Wallenius.
Many politicians, and also high military officers, were initially sympathetic with the Lapua Movement, as anti-communism was the norm in the educated classes after the Civil War. However, excessive use of violence made the movement less popular within a few months.
In the Civil War Ostrobothnia was one of the most important strong-holds and bases of the White army, and anti-Communist sentiments remained extremely strong in Ostrobothnia. Late in November 1929 the Communist Youth Movement arranged a happening in Ostrobothnian Lapua. This infuriated the locals, who violently made an end to the meeting. On December 1st an anticommunist meeting was held, attracting more than 1,000 people. A ban of all communist activities was demanded.
Marches and meetings were arranged throughout the country. On June 16th, 1930, more than 3,000 men arrived to Oulu in order to destroy the print and office of the Communist newspaper Pohjan Voima. However, the last issue of Pohjan Voima had appeared on June 14. The same day, a Communist print in Vaasa was destroyed. A so-called "Peasant March" to Helsinki was a major show of power. More than 12,000 men arrived in Helsinki on July 7th. The government yielded under the pressure, and communist newspapers were outlawed in a Proctection of the Republic Act.
After this, the Lapua Movement became even more extreme. Their activities included harassing individual Communists, Social Democrats, Pacifists, Liberals and labor unionists. One common treatment was "muilutus", which started with kidnapping and beating. After that the subject was thrown into a car and driven to the border of the Soviet Union.
Meetings held by leftist and labour groups were also interrupted, often violently. More than 400 meeting locals owned by the labour movement were closed by Lapua activists.
On October 14th, 1930, the popular ex-president Kaarlo Juho Ståhlberg and his wife were kidnapped, beaten and driven to Joensuu (i.e. not really to the Soviet Union this time). This was intended as a first stage of a coup d'etat, but it backfired and the general support of the movement collapsed. Moderate people left the movement, and extremists took the stage. Never-the-less, a few months later the Lapua Movement was capable of not only demanding "their man" appointed President of Finland by the Collegium of Electors, which only weeks before had been chosen in a nation-wide voting, but a sufficient number of the electors followed the Lapua Movement's request, disregarding the intentions they had declared during the election campaign. The Movement's man, Pehr Evind Svinhufvud, was elected.
In February 1932 a Social Democrat meeting in Mäntsälä was violently interrupted by armed Lapua activists. The event escalated to an attempted coup d'etat known as the Mäntsälä Rebellion (Mäntsälän kapina), led by the Chief of Staff of Finland's Army, general Wallenius. Despite the appeals of Wallenius, the army and the White Guards were largely loyal to the government. Many historians believe the main reason for the failure was poor planning. The rebellion ended after the President Svinhufvud had held a radio speech to the rebels. After a trial, the Lapua Movement was banned on November 21st, 1932. Wallenius and about 50 other leaders were sentenced to prison. The conviction was however very lenient, compared to the treatment of the defeated Reds after the Civil War.
Finland's foreign relations and reputation were without doubt damaged by the broad support the Lapua Movement initially was shown by Finland's elite, and by the ties between the Movement, the White Guards and Finland's army. Particularly the Scandinavian neighbours came to view Finland with even more suspicion, by and large neglegting that Lapua's chosen president actually had executed the Movement.
Ironically, the banning was done under the Proctection of the Republic Act, which originally was dictated by the Lapua Movement.