The Medieval Fortress of Bo Jonsson (Grip)

Bo Jonsson (Grip) acquired Bjärka gård in 1367 and likely constructed the fortress known as Bjärkaholm between 1367 and 1370. The site is located on Bosholme in the Stångån river, roughly one kilometer north of modern-day Bjärka-Säby in Östergötland. According to Holger Rosman, Jonsson chose this location for its strategic position near the trade route between the cities of Östergötland and Kalmar, as he required a fortified castle for protection before he began his larger acquisitions of property.

Bjärkaholm consisted of a large building in the west, measuring 10 times 19 meters, which likely had multiple stories and a watchtower. A well was built directly into its wall. About 20 meters northeast of this main building, several economic structures made of stone and wood were situated within a ring wall and possibly a wooden palisade. Nearby, a stone setting likely served as a bridgehead.

Records show the site was active for several decades; a letter from Bo Jonsson (Grip) was written there in 1385, and a letter from Ulf Jonsson (Aspenäsätten) was dated 1390. In 1396, a decision was made to demolish several castles that were no longer desired, and it is possible Bjärkaholm was destroyed as a result. There is no evidence that the site was destroyed during active combat.

Today, the ruins are overgrown with dense deciduous forest, making it difficult to get a clear overview of the area. When the Kinda Canal was built in the 1850s, the water level in the Stångån dropped, drying the riverbed and making the ruins accessible on foot. While much of the original building material has been moved, oral tradition suggests the stones from Bjärkaholm were used to construct the old castle at Bjärka-Säby.

Sources: Wikipedia, OpenStreetMap, Wikidata, Wikimedia Commons