In February 1918 Mannerheim wrote his famous "sword scabbard" order of the day, in which he said that he would not put his sword into the scabbard until eastern Karelia was free. After the Finnish Civil War there was much public discussion about joining eastern Karelia to Finland.
Earlier attempts in 1918 to Petsamo and White Karelia had failed, partly due to a passive attitude of the Karelians. Later the British occupied White Karelia.
The expedition cosisted of about 3000 volunteer troops that crossed the border during the spring of 1919 with the goal of annexing Olonets Karelia to Finland. They advanced as far as the River Svir and Petroskoi. The Finns had hoped that the Karelian population would have joined the troops as volunteers but only a few did and their morale was never very high.
The expedition was soon attacked by the bolsheviks and was forced to retreat back to Finland.
Aftermath
The only "gain" from the expedition was that the parish of Porajärvi declared that it wished to join Finland. As had the parish of Repola already done in 1918. Some volunteer forces were left in these two villages. In the treaty of Tarto in 1920 Finland and Soviet Union agreed on their common border. Repola and Porajärvi were left on the Soviet side and the Finnish troops had to be withdrawn before February 14 1921. The young police chief in Repola, Bobi Sivénin shot himself in protest.