The area around the city of Karlshamn was a part of Denmark up until the peace in Roskilde in 1658. After this peace treaty the province of Blekinge were transferred to Sweden and the Swedish king and his men went down to their new possessions and realized the area around Karlshamn had a great location to set up a harbor and a stronghold in the new southern part of Sweden. The city was founded in 1664 and would be fortified to protect the new possessions in case of new wars with Denmark.
The Danish army attacked the city twice in 1676-78 in an attempt to regain the old Danish possessions – but in the end the Danish army failed and the area was never liberated from the swedes. After the Danish attacks the city prospered in the following century. The city took advantage of its location to trade with the countries on the southern shore of the Baltic – including some areas which were actually controlled by the Swedish king.
During the Napoleonic war the city prospered since Sweden was allied with England and the English navy ruled the waters of the Baltic Sea making it impossible for the continental merchant ships to trade with the rest of the world.
The city is dominated by straight streets so you can see the city is a planned city. This way you can see the town isn’t an old settlement with the old twisted roads you find in the older cities around Denmark. The city is pretty quiet today and you can easily have a look around the old streets and the harbor where there is still an industrial harbor keeping the long tradition of a harbor town alive.