At the outbreak of the First World War in August 1914, he joined the Imperial German Army and served as a front line soldier in the 46th (Lower Saxony) Field Artillery Regiment.

[2] In the Reich and Prussian Ministry of Economic Affairs, Brinkmann in 1934 worked under Reichsminister Hjalmar Schacht, initially as a Generalreferent (general consultant).

On 4 February 1938, the new Reichsminister of Economics, Walther Funk, promoted Brinkmann to principal State Secretary of the ministry, replacing Hans Ernst Posse.

[2] Brinkmann was also a board member of the Vereinigte Elektrizitätswerke Westfalen [de] (United Electricity Works of Westphalia) and the Bank for International Settlements.

[6] On 11 May 1939, due to the duration of his illness, Brinkmann was retired and admitted to a psychiatric hospital in Bonn, where he remained in a closed ward until the end of the Second World War.