 Nyora kupfuurira kweiyi ndima - Musi wa20 Mbudzi 1913, akasimudzirwa kuva Oberleutnant mutungamiri wekutanga uye akagadzwa semubatsiri kumukuru we80th Field Artillery Regiment. Chirongwa ichi chakatumirwa kuKolmar muAlsace-Lorraine uye pakatanga Hondo Yenyika I vakaona chiito pamuganhu wekumabvazuva kweGermany unozivikanwa seHondo yeFrontiers. Chikamu chechi39 chakazotora chikamu muMujaho weGungwa pakati paGunyana naNovember 1914, izvo zvakaunza Chikamu chechi39 kunzvimbo iri pedyo neRwizi rweYser muFlanders, Belgium. Pavaiva muchikamu chino chemberi, Chikamu chechi39 chakarwa muHondo yeYser. Muna Kubvumbi 1915, Bader akasimudzirwa kuva Hauptmann kaputeni uye akagadzwa semubatsiri kumukuru we39th Field Artillery Brigade. Pashure pokuendeswa kuchamhembe kwakadziva kumabvazuva kweFrance mukuvamba kwa1916, boka racho rakasimbisa kurwisa kweGermany paVerdun. Munguva yasara yehondo, Bader akaramba ari mu39th Division, iyo yakarwa muhondo yeSomme, Hondo yechipiri yeAisne, Hondo yePasschendaele, uye kurwisa kweGermany kwegore ra1918. 