After attending the Cadet corps, on 23 April 1874 Kosch graduated as a Sekonde-Leutnant in the (4th Lower Silesian) Infantry Regiment No.

After a number of regimental and staff assignments Kosch was promoted to Oberst on 22 April 1905 and took command of the Landwehrbezirk II in Berlin.

Brandenburgisches Infanterie-Regiment „General-Feldmarschall Prinz Friedrich Karl von Preußen“ Nr.

[1] After the outbreak of World War I he led his division into the Loraine region on the Western Front.

Army Corps in Lithuania, where his troops opposed numerically superior Russian forces.

After initial tactical setbacks Kosch and his men finally won the Second Battle of the Masurian Lakes.

The multi-day battle at Argesch, in late November to early December 1916, culminating in a Romanian defeat, led to the occupation of Bucharest and the crumbling of Romania's western and northwestern front sectors.