Kammala jumla mai zuwa: Sarauniya Christina ta Sweden ta ɗaukaka shi a matsayin baron a shekara ta 1651, kuma a ranar 28 ga Mayu, 1654, ta sanya shi lamba. A shekara ta 1652, ta sanya shi a matsayin Sarkin Maigidan Sarki. A cikin Yakin Poland, Douglas ya kasance a cikin hidimar Sarki Charles X. Ya kasance tare da sarki a
Yaƙin Warsaw a shekara ta 1656. A ranar 13 ga Mayu, 1657, sarki ya ba shi mukamin marshal.