Salvius was, next to Axel Oxenstierna, one of Sweden's most capable and influential diplomats of his time and correspondent of Hugo Grotius.
Salvius resided in Hamburg from 1631 till 1634 as a general war commissioner in Lower Saxony but moved back to Sweden until 1636.
Salvius made a fortune marrying the (much older) widow of a goldsmith who owned several properties in the Salviigränd alley, which was named after him.
When it became clear Johan Oxenstierna was not capable to fulfill his task neither diplomatic nor mentally, Salvius managed to push through the view of Queen Christina.
[1] In 1648 Salvius considered it “a great miracle that we hear of revolts by the people against their rulers everywhere in the world, for example in France, England, Germany, Poland, Muscovy, and the Ottoman Empire,” and wondered “whether this can be explained by some general configuration of the stars in the sky.” In 1650 he went back to Stockholm.