 Nyorai kupfuurira kweiyi ndima - Akagadzwa semukuru mukuru muna 1903 uye akasimudzirwa kuva lieutenant muLife Regiment Dragoons K 2 muna 1906. Douglas akanga ari lieutenant muGeneral Staff muna 1913 uye akashanda semukuru mukuru mukuru muvashandi ve1st Army Division I. arméfördelningen kubva muna 1914 kusvika muna 1917. Akakwidziridzwa kuva kaputeni muna 1916 uye akaita gore rimwe chetero rwendo rwekudzidza kunharaunda yeGalicia muCentral-Eastern Europe. Paakadzokera kuSweden, Douglas akashanda semudzidzisi wenhoroondo yechiuto paRoyal Swedish Army Staff College muStockholm kubva muna 1917 kusvika muna 1918 uye semukuru wevashandi muhofisi huru yeFinland panguva yeHondo yeVanhu yeFinland muna 1918. Munguva yake muFinland muna 1918, akazova kaputeni uye lieutenant colonel muFinnish Army uye akatora chikamu muHondo yeLänkipohja uye Hondo yeTampere. Kudzokera kuSweden, Douglas akava ryttmästare uye squadron mutungamiri muHupenyu Regiment Dragoons muna 1919 uye akadzidzisa hondo yepasi kuRoyal Swedish Naval Staff College pane uye pakati pe1919 ne1929. 