After the establishment of the Prussian Navy in 1849, he entered as an auxiliary officer, becoming a Kapitänleutnant (KL—Captain Lieutenant) in 1855 and a Korvettenkapitän (Corvette Captain) in 1859.

Gazelle struck a merchant ship in Constantinople in February 1867; Henk had been asleep at the time of the collision and the investigation placed the blame for it on his executive officer, KL Johannes Weickhmann.

Henk was chosen in large part to reduce the threat to the position of Stosch, a general of the Prussian Army with no naval experience.

Henk was an officer of middle-class background, had initially served in the merchant marine before entering the navy, and though he had been exonerated by the investigation into the Gazelle collision, it nevertheless had damaged his reputation.

Between 1890 and 1893, Henk served in the Reichstag as a member of the German Conservative Party, representing the electoral district of Ueckermünde-Wollin.