In the Svenskt biografiskt lexikon, the standard biographical dictionary begun in 1917, it's claimed that the later Field Marshal Carl Gustaf Dücker (1663-1732) had served in the French army during the Nine Years War and after his return home to Livonia served as a volunteer during the siege of Riga in 1700. This is perhaps not quite correct, as on 15 February 1700 Governor General Dahlbergh orders the captains "Stahl and Dücker" to remain in Riga and not return to the Netherlands. The letter filed under that date is however undoubtedly addressed to just "Stahl", but a similar can be found mistakenly placed under the date 20 March. In this letter the Governor General tells Dücker that he understands that the latter's leave of absence has come to an end and that he must return to his regiment in France, but Dahlbergh will not permit it because of the Saxon attack. Instead Dücker should join in the defense of the city, being assured that this would not cause him any disrepute because a loyal subject must always put his own King before any foreign power.
LVVA, Fond 7349, op. 1, vol. 52, Copy book of outgoing correspondence in German