Swedish pacifism developed greatly after loosing the over sea (Baltic sea that is) empire. Squeezed between two emerging greater powers - Russia and Germany - war was for a very long time not an option. Sure there was the late 19th century dreams of reqonquering Finland (from Russia) and uniting Scandinavia under the Swedish kings, but there was no possibility to do so. Sweden went from having a war (almost) every year up to 1814 to not having any wars at all. Thus those politicians and thinkers who scorned war as a mean were succesful, while the warhungry was unsuccesful. I think this left a mental-cultural impression on how to be succesful in life.

BTW, there was some contemplation on attacking Russia in 1914 to get Finland back, but it was deemed impossible given the state of Swedens military. (Good topic for contrafactual history though, given how even ww1 was.) And Sweden sent volonteers to Finland during the winter war (1939-1940), with equipment, officers and all. But Sweden has not been in a formal war since 1814, and that might be some kind of record.

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