There is actually a lot of Swedish people who could not answer straightly why we celebrate the national day. Face it, we aren’t the most nationalistic people, we are getting more multiculturalistic every day — which I think is a good thing done properly — and it is also the day of the Swedish flag. We have not have war in a century, we have never really been occupied in modern times, except the Danish who we warred with for a long time ago and they never really occupied the whole country.
Until 2005 we actually did not have a proper national day. We had the day of the Swedish flag. However a proposition was made and put in front of the government stating that many people who came to Sweden found it strange we did not have a national day and so it was made into a national day, a national bank holiday, remains the day of the Swedish flag as well.
To give it a proper holiday the Swedish unions and the merchant associations sat down to discuss how to make it without losing too much money on it. It was not possible to create a new holiday said the merchant associations and so a trade was proposed, changing the Whitmonday into an ordinary day and instead making the 6th of June a proper bank holiday, which it wasn’t before.
The day has been called the ”Gustaf Vasa day” when Gustav Vasa was elected king of Sweden and the Kalmar union finally ceased and Sweden became a sovereign state. This was 6 june 1523. The Kalmar Union was a union between the kingdoms of Sweden, Norway and Denmark, established in 1397. It allso encompassed Finland (part of Sweden at the time), Greenland, Faroe Islands, the Orkney islands and the Shetlands. After Sweden left the Union Denmark and Norway remained until 1536 when it was finally dissolved. The union was formed in Kalmar in Sweden and thus the name.
The connection with the day is fairly loose. Most Swedes enjoy it as a day off mainly, it’s not celebrated by far as much as the norwegians do on their 17th of May. I have never been very nationalistic so I am not very bothered about this.