I have become interested in Scandinavia over the past few years, thanks to my sister's marriage to a Swedish man. The links between the region and the Civil War are considerable. Near my hotel at Djugarden in Stockholm, I discovered a monument to naval engineer and inventor John Ericsson. His creation, the USS Monitor, helped the Union Navy win the Battle of Hampton Roads in March 1862 against the CSS Virginia. Here's a picture of it.
Many thousands of Scandinavians fought in the the war, mostly for the Union. One of the more notable ones was Colonel Hans Heg. Originally from Norway, he emigrated to the US. He commanded the 15th Wisconsin Infantry, a unit comprised of Scandinavian men. This must have been an interesting arrangement given tensions between Norway and Sweden at the time. The two countries had been united, unhappily, into a single kingdom in 1814, lasting until 1905. Danes and Finns had issues with the two as well. I'm also sure other regiments with Scandinavians had similar situations. Heg led the 15th wish distinction in the western theater, Shortly after being promoted to brigade command, he was killed in action at Chickamauga in September 1863. Here's a picture of his memorial on the battlefield.