[3] In January 1911, he was promoted to the rank of Battleship Captain, and was appointed Deputy Commander of the armored cruiser Friedrich Carl.

[1] At the beginning of World War I, Michelsen was appointed commander of the armored cruiser SMS Prinz Adalbert.

In addition to that command, from 20 April to 3 July 1915 he also held the position of Chief of Staff of the Scout Forces in the Eastern Baltic.

In July 1915, the SMS Prinz Adalbert was severely damaged thanks to a torpedo attack, and Michelsen managed to tow it back to Kiel, running 240 nautical miles backward.

[4] In August 1915, he was appointed Chief of Staff of the Supreme Command in the Eastern Baltic, and on 14 April 1916 he became Commander-in-Chief of the Torpedo Boats (Erster Führer der Torpedobootsstreitkräfte).