The Civil Guards, as well as the opposing Red Guards, were formed to fill security deficits caused by Russian uprisings. At the beginning of 1918, the Civil Guards were still in the middle of getting armed and organized. Old officers and NCOs had initially served as instructors, but returning jägers had brought valuable training help in the autumn.
At the turn of the year, a course to shape Civil Guard leaders out of high school graduates was held in Vimpeli. Some 200 students were trained by jägers, and the Vimpeli Military School is considered the beginning of the Finnish Reserve Officer School.
An armed conflict between the local Civil and Red Guards took place in Vyborg on January 19th, forcing the Civil Guard to retreat from the town. In the following days, it clashed multiple times with the Reds along the road to Saint Petersburg. Similar conflicts occurred in other areas as well.
As the situation intensified, on January 25th the Senate appointed the Civil Guards as forces of the Government, henceforth also called the White Army of Finland. The Red Guards started a revolution in Helsinki the following day. Over the next 24 hours, the Civil Guards, led by General Mannerheim, began disarming Russian garrisons in Ostrobothnia. A civil war had begun.
On January 26th, a course to train NCOs for the Civil Guard Army commenced in Vöyri. The 1,400 students had only started their second day when they became involved in military operations. They were trained amidst battles until the end of the war in May.
At the beginning of the war, some 20,000 Civil Guard troops had voluntarily joined the ranks. Included in the forces were almost 200 jägers. A dividing front line ran through the country, forcing the southern Civil Guards to retreat. On the northern side of the line, the Civil Guards seized the industrial areas controlled by the Red Guard.
The Reds launched a general assault to the North in February, but the Civil Guard troops managed to hold their ground. Most of the jäger advance party that had arrived in Vaasa on February 18th was immediately sent to serve as leaders for the Civil Guards.
Although the White Army bolstered its ranks with troops recruited in February, the numbers were not enough. At the end of the month, compulsory military service was decreed by law. The main body of the jägers began training the conscripted forces.
Commander-in-Chief Mannerheim could not wait for the new troops to be ready. He initiated a Civil Guard operation to seize Tampere in March, surrounding the town but being unable to strike to the heart. At the start of April, a successful occupation of Tampere virtually decided the outcome of the war. The key players at the tail end of the war were German and Finnish conscripts.
To celebrate the end of the war, the White Army held a parade in Helsinki on May 16th. The 12,000 soldiers participating included 4,700 Civil Guard members.
During the spring, Reds were arrested, interrogated, and sentenced in court martials. Reconnaissance units gathered and evaluated their personal information, determining potential adversaries. The Civil Guards visited prison camps to identify local Reds for execution, carrying out the punishments until the task was transferred to judicial authorities in June.
The Civil Guards continued to catalogue persons marked as enemies over the summer. Statements on members of the Red Guard were needed in courts of criminal justice. They also remained as guards in towns and prison camps. After the war, drafting of national defence plans commenced under the lead of the Germans. The establishment of new Civil Guards was forbidden, and the Civil Guard districts were abolished. A voluntary armed organization seemed to have no place in the young country’s defence regime.