Osterkamp was born in Rölsdorf near Düren, West Germany, and grew up in Aschersleben,[4] modern day Saxony-Anhalt.

He was born in 1892 as the second son of the factory owner Hermann Osterkamp and Anna Wilhelmine née Blank.

During 1915–1916, he served as an air observer, and became the first German pilot to fly a land-based aircraft to England on a reconnaissance-mission.

Osterkamp claimed his first (but unconfirmed) kill on 6 September 1916 as an observer to pilot Leutnant zur See Wilhelm Mattheus in a LVG C.II two-seater aircraft.

[4] In March 1917, he joined the Kampffliegerschule (Combat pilot school) in Putzig and then joined Marine Feld Jagdstaffel 1 on the 14th of April 1917[4] On 21 March 1917, Leutnant Osterkamp took command of Marine Feld Jagdstaffel 2 [6] He scored a total of 32 victories during the war,[3] and was awarded the Prussian military order Pour le Mérite[3] on 2 September 1918,[7] and was one of the last individuals to receive it.

[10] World War II in Europe began on Friday 1 September 1939 when German forces invaded Poland.

He then served in a number of staff positions until being appointed Inspekteur der Luftwaffen-Bodenorganisation (Inspector of Luftwaffe ground organisation) in 1944.

(question mark) indicates information discrepancies listed by Prien, Stemmer, Rodeike, Bock, Mathews and Foreman.