The oldest evidence of settlements in the Mikkeli region date back to the Comb Ceramic culture of the Stone Age, around 4000–2000 BCE. The known findings from this era are mostly of settlements.
Increased significance in the 18th century
Already in the Middle Ages, the area of the parsonage of Suur-Savo, or greater Savonia, was an important pitstop on the old Vanha Savontie road. In the beginning of the 17th century, the area received its present name Mikkeli after the Archangel Michael, the patron saint of the local church. The first written mention of the name Mikkeli dates back to 1604, to a collection of Swedish royal correspondence.
In the beginning of the 18th century, hostilities between Sweden and the Russian Empire made Mikkeli increasingly important due to its strategic location. When Sweden lost the city of Vyborg to the Russians in 1710, the episcopal sees were ordered to be temporarily transferred to Porvoo and Mikkeli. For the development of the region, the fact that the crown had big plans for Mikkeli to become the economic centre of eastern Finland was very important. In 1744, Mikkeli received the old trading rights from the nearby town of Lappeenranta. After the Treaty of Turku of 1743 between the Russian Empire and Sweden, but also later in the 18th century, the establishment of Mikkeli as a market town was much discussed, but such plans were put on hold for the time being.
The renowned Savonian light infantry regiment, established in 1770, held its military exercises in Mikkeli, and when the Savonian units were formed into the Savon prikaati, the “Savonia Brigade,” in 1775, Mikkeli retained its central position. During the Russo-Swedish War of 1788-90, the significance of Mikkeli grew even more pronounced as the town operated as a strategically significant traffic and communications hub. The plans to fortify the Naisvuori and Akkavuori hills and visits of the King to Mikkeli at the end of the era of Swedish rule also tell of the growing military significance of the town. The fact that both Gustav III and Gustav IV Adolf, the Swedish kings, visited Mikkeli, also says something of its importance in that era.
City of Mikkeli is established
In 1809, Finland became an autonomous part of the Russian Empire, the Grand Duchy of Finland, and a new division of the land into provinces was in order. In 1831, the northern part of the then-Province of Kymenkartano was made into the Province of Mikkeli, during the reign of Emperor Nicholas I of Russia. On 7 March 1838, Nicholas I proclaimed that a town to be called Mikkeli was to be established in the parish of Mikkeli. In February 1842, Mikkeli was given its coat of arms, designed by Governor Otto Boije (1840–47).
City of headquarters in the Finnish wars
Historically, Mikkeli is perhaps best known as the city of headquarters in the Finnish wars of the 20th century. The first time Mikkeli acted as the headquarters was in 1918 at the end of the Finnish Civil War, from 11 April to 16 May, when the military leader of the forces of the Senate of Finland, General Carl Gustaf Emil Mannerheim, moved his headquarters from Ostrobothnia to Mikkeli, as the front moved east towards Karelia after the city of Tampere had fallen to his troops.
The start of the Winter War in November 1939 meant that Mikkeli took centre stage, as the headquarters of the Finnish Army was moved there. In terms of the total strategy of the war, Mikkeli was ideal as the place from which to command the war effort. Mikkeli served in the same capacity during the Continuation War, which lasted from 25 June 1941 to 19 September 1944. The Lapland War was prosecuted from Mikkeli, and the last units of the main headquarters left the city in the summer of 1945.
A strong regional centre
Mikkeli was the capital of the Province of Eastern Finland from 1997 to 2009. With the municipal mergers, Mikkeli has developed into a strong regional centre in South Savo. The last municipalities to join Mikkeli were Ristiina and Suomenniemi in 2013.