. At the outbreak of the
Great Northern War, Psilander served as
Admiral Cornelius Anckarstjerna's
flag captain, escorting
Charles XII of Sweden and the
Swedish Army to
Pärnu. After serving as a
frigate captain in the
Bay of Finland, he became
captain of the 56-gun
ship of the line Öland and charged with convoying Swedish merchantmen during the
Great Northern War. During one of these expeditions, Psilander encountered a Royal Navy squadron of eight ships of the line and one frigate under
Rear-admiral William Whetstone on 7 August 1704. Whetstone demanded the Swedish salute his ships as they were in English waters, though Psilander refused as he was under strict orders by Charles XII to not salute foreign ships first. This led to
a four-hour battle, during which the English captured
Öland along with the merchantmen she was convoying, though they were soon released and returned home. Psilander commanded a ship of the line in the 1710
Battle of Køge Bay, and became
deputy superintendent of the Swedish
naval shipyard in
Karlskrona in the same year. Promoted to
Schoutbynacht and Admiralty commissioner in 1712, he was also
ennobled the same year. Patronised by Charles XII since his defeat at Orford Ness, Psilander was promoted to
vice admiral and appointed superintendent of the Karlskrona shipyard in 1714 before becoming a full admiral in 1715. In 1716, he was appointed as the
governor of Gotland, which was repeatedly raided by the
Imperial Russian Navy. Psilander's mission was to organise the local population in a homeland defence, but this proved unfeasible when the Russian
galley fleet under Admiral
Fyodor Apraksin carried out a week-long raid on parts of the island in July 1717 . Psilander then had to devote himself to recruiting personnel and obtaining supplies and tax funds for the King's last military operations. ==Later life==