The region of Kainuu was brought under Swedish rule in the 12th century when Sweden invaded Finland, but it was not until the beginning of the 17th century that the Swedish crown began to consider the region's strategic value in the event of an attack by the Russians.
In 1604 the Swedes began construction of a fort at an important crossing-place on the river Kajaaninjoki. The fort was situated in the middle of the river on a small island which was connected to both banks of the river by bridges. The original fortification consisted of two stone towers and an enclosing wall.
Construction of this first fortification was completed by 1619. A village grew up near the castle and became known as Kajaani. In 1651 Kajaani, which was home to less than 400 people, received its charter meaning that it had the rights and priveledges of a town.
Count Per Brahe, the governor-general of Finland, had recognised the potential of this small village situated on a crossroads in a prime tar-producing region. A mayor was appointed and a system of magistrates set up to govern the new town.
Per Brahe also ordered that the castle be strengthened. This work was carried out from 1651-1666 and included rebuilding the castle's internal buildings, which had hitherto been made of wood, in stone.
By 1666 the castle, although not a perfect fortification, presented a formidable obstacle to any invasion from the east. Kajaneborg, as the castle was known in Swedish, took the form of a long rectangle with a circular tower at each end. The outer wall of the castle had a wider section at the eastern end.
These sections had embrasures allowing cannon to fire along the flanks of the fortification. Cannon in the towers could fire downstream and upstream as well as providing some flanking fire to cover the end walls.
Kajaani grew slowly, but the tar trade thrived, and the town was to become the world's largest tar producer. The tar barrels were brought to Kajaani and then taken across the Oulujärvi lake and down the river by barge to the port of Oulu on the Bothnian coast, from where they were shipped all over the world. Kainuu tar was used to waterproof merchant and naval ships of great imperial powers like Great Britain, France and Spain.
In addition to its function as a military outpost, the castle was the seat of government for the region and was used as a prison. The famous Swedish writer Johannes Messenius was imprisoned in Kajaani Castle from 1616 to 1635.
In 1716, during the Great Northern War, a Russian force invaded Kainuu and laid siege to Kajaani castle. After a bitter siege of 5 weeks, the garrison surrended having run out of food, powder and firewood. The Russians blew the castle up in March 1716.
Visiting Kajaani Castle
Kajaani castle (known as Kajaaninlinna in Finnish) was slighted by the Russians following the 1716 siege and was never repaired. A modern road bridge has been built across the middle of the castle, which spoils the remains as well as providing easy access to them.
The walls of the castle survive up to the second storey in places, but it is not known exactly what the castle originally looked like above the second floor. Some theories have the towers being 5 storeys high, but this is unlikely. It is probable that the walls had a roofed parapet on the second storey, and the towers may have been a storey higher and would also have been roofed.
Kajaani castle can be visited for free at any time. There are steps from the side of the bridge that lead down into the centre of the castle. It is situated just to the north of the centre of town, a short walk from the train station.