The earliest period of Swedish colonization of Finland proper (in the area around the city of Turku) occurred at the end of the 12th century, and could be considered a part of the religious and political movement known as the Northern Crusade. The Swedish monarchs and nobles would have had numerous reasons for the effort including
•suppression of piracy in the Gulf of Finland and Aaland archipelago.
•conversion of Finnic tribes to Catholic Christianity.
•creation of markets, establishment of feifs, and access to raw materials.
•to check the influence of Novgorod, and counter the spread of the “heretical” Orthodox creed.
Indeed, the spread of Swedish language and construction of fortresses goes hand in hand with the construction of Catholic churches and cathedrals in the early period.
Skipping ahead from the 1200s up to the 1400s, Sweden joined Denmark and Norway in a union of the skandinavian kingdoms called the Union of Kalmar, which was dominated by Denmark. Under Gustav Erikson, later King Gustav I Vasa, Sweden (and Finland) left the Kalmar Union in 1523. Gustav Vasa profoundly changed the Swedish monarchy, weakening the power of the nobility and church to enhance his own power. Following a dispute with the Pope about the appointment of Bishops, Gustav allowed the spread of the Lutheran church in his kingdom. This period also saw the administration of the provinces in Finland come under the supervision of royally appointed bailiffs, rather than being administered by local Bishoprics and noble families (who tended to be Germans appointed by pre-Kalmar kings).
Following Gustav I, his sons Eric XIV and John III ruled. John originally ruled as Duke of Finland during his brother’s reign, and used his power base in Finland to depose his mentally unstable brother. John had strong catholic sympathies, and under his reign and that of his son Sigismund, Sweden would see the reintroduction of many Catholic ceremonies and the drift back towards Catholicism being the state religion.
Sigismund was troubled in that his Catholicism as well as his duties as King of the Polish-Lithuanian Commonwealth put him at odds with his Swedish nobles, and he was deposed in turn in favor of Gustav I’s youngest son Charles IX. During this conflict in Sweden proper, the provinces of Finland saw what has been called the Cudgel War, where peasants rebelled against burdensome and exploitative nobles and military garrisons. Charles IX expressed support for the peasantry, but his forces were engaged fighting Sigismund in Sweden.
The period of Charles IX reign would see the lessening of the old rivalry with the Russian principalities (Muscovy was descending into the Time of Troubles) and a heightening of rivalry with Poland-Lithuania ruled by the disgruntled Sigismund who never relinquished his claim to the crown of Sweden. In fact, this period would see Russia as the playground for Polish and Swedish invasions and puppet Czars (something never mentioned in discussions of Charles XII/Napoleon/Hitler).
Charles IX was succeeded by his illustrious son Gustav Adolph, also known by his latinized name Gustavus Adolphus. Gustav Adolph’s reign saw the conquest of Skane from the Danes by the young monarch, an extended war against his cousin, Sigismund, in Prussia, and eventually Swedish intervention in the 40 years war. During this long period of war, Finnish cavalry regiments known as Hakkapeliitas made a name for themselves for their endurance and savagery. Actually, Jean Sibelius wrote a concerto about them known as the Hakkapeliita March.
At the end of Gustav Adolph’s reign, Sweden could be considered one of the “great powers” of Europe to come out of the 40 years war, along with France.
However, Swedish strength would ebb away with the reforms of Peter the Great of Russia. King Christian XII fought the Russian Czar to a standstill in the early phases of the Great Northern War in 1700, but the Swedish monarch made the drastic mistake of engaging in a long and inconclusive war with Poland while the Russians recouped their strength. The result was Russia took over the territory of Estonia, gained access to the Gulf of Finland including the site on which St Petersburg was constructed, as well as the loss of Viipuri/Vyborg, the lynchpin of the eastern defenses of Finland.
Finally, Sweden would lose the entirety of Finland in the 1808-09 Finnish War.