[1] A great-grandfather was the court pharmacist, polymath and friend and discussant of Immanuel Kant, Karl Gottfried Hagen (1749–1829).

Curt von Hagen followed his father's military career and joined the Prussian Army as a field artillery officer in 1878.

From 1893 onwards he was the chief administrator of the Jomba tobacco plantation for the Astrolabe Company near Friedrich-Wilhelmshafen in German New Guinea.

On a business trip to Herbertshöhe in May 1897, von Hagen learned from Albert Hahl of the 1895 murder of the travel writer Otto Ehrenfried Ehlers and some of the police soldiers accompanying him.

Five days after the Imperial German Navy had bombarded the island with the cruiser Falke,[2] the locals killed the two murderers and, after handing them over to the colonial administration, placed their heads on display in Stephansort on 19 August as a deterrent.