He had attended the War Academy at Munich for three years (1895–98) but was not awarded the full qualification to join the general staff, despite excellent performance.
The work of his office (employing around 2,500 people at the end of the war) was highly regarded and brought him the recognition of the military command, industrialists and trade unions.
However, in 1916/17 there were sharp differences with general Wilhelm Groener, head of the Kriegsamt, in connection with the Hindenburg Programme and the Auxiliary Services Act (1916).
When the cabinet of Philipp Scheidemann took office in February 1919, he became Reichsminister für wirtschaftliche Demobilmachung (Minister for Economic Demobilisation) until the Ministry was dissolved on 30 April 1919.
[1] His difficult task was to move the German war economy to a peace footing against a backdrop of revolutionary conditions and with responsibilities and power structures still in flux.
The economic depression with rising unemployment and the devaluation of the currency caused by the post-war slump presented important obstacles on the way towards an industrial structure geared to the new requirements of peace-time Germany.
There was considerable overlap between Koeth's portfolio and the Ministries of Finance, Economic Affairs and Labour, resulting in conflicts with Eugen Schiffer, Rudolf Wissell and Gustav Bauer.
It was so short-lived, though, that he was unable to make a major contribution to policy - although during his period in office the Papiermark was replaced with the Rentenmark, which laid the foundation for the stabilisation of the currency and the end of hyperinflation.