[1] On completing his legal studies, he entered the service of the state in 1837; and after holding a series of minor posts was transferred in 1848 to the ministry of commerce, which was to be the sphere of his real life's work.

The states of the German Confederation, including Prussia and the Austrian Empire, had realized the influence of commercial upon political union.

Delbrück now began, with the support of Otto von Bismarck, to apply the principles of free trade to Prussian fiscal policy.

In October 1870, when the union of Germany under Prussian headship became a practical question, Delbrück was chosen to go on a mission to the South German states, and contributed greatly to the agreements concluded at Versailles in November.

On the introduction of Bismarck's plan for the acquisition of the railways by the state, Delbrück resigned office, nominally on the ground of ill-health (June 1, 1876).