Portrait of Frederick III, Duke of Holstein-Gottorp by Anselm van Hulle
He had ambitious plans concerning the development of sea trade. With this purpose he established Friedrichstadt in 1621, in sympathy with city of Glückstadt established in 1617 by Christian IV of Denmark. Furthermore, he attempted to find a commercial way to Russia and Persia that would not pass around Africa.[citation needed] For this reason he sent on 6 November 1633 the expedition from Hamburg to Moscow under the management of a commercial agent of Otto Brüggemann and a ducal adviser, Philipp Crusius, and with Adam Olearius as secretary.[1] On 14 August 1634 the delegation arrived at Moscow. Although it was not successful in concluding a commercial agreement with Tsar Michael I of Russia, nevertheless, immediately after the return of the delegation to Gottorp on 6 April 1635, Frederick began the preparation of the following expedition.[citation needed] In 1636, he sent his delegation to Persia, and in 1639 Safi of Persia sent a return delegation with presents for the Duke.[1]
The difficult task of leading the country through the Thirty Years' War confronted Frederick. He tried a policy of neutrality, which meant in practice the refusal of the union with Denmark and inclinations toward Sweden.[citation needed] In 1654 he hosted the recently abdicated Christina, Queen of Sweden. She wrote to her successor to recommend two of his daughters as potential brides. Thus, he married his daughter Hedvig Eleonora to King Charles X of Sweden.[1] Since the Swedish attempt at being the Great Power ultimately failed, Frederick's pro-Swedish policy led to the weakening of the house of Holstein-Gottorp.
Frederick died in 1659 in the fortress of Tönning, while the fortress was besieged in the course of the Second Karl Gustav War between Denmark and Sweden.
Granlund, Lis (2004). "Queen Hedwig Eleonora of Sweden: Dowager, Builder, and Collector". In Campbell Orr, Clarissa (ed.). Queenship in Europe 1660-1815: The Role of the Consort. Cambridge University Press. pp. 56–76. ISBN0-521-81422-7.