In 1857, Siemens began studying law in Heidelberg just before beginning his one-year military service in Berlin in 1858.

After passing his state examination in 1860, Siemens worked as a clerk for the district courts in Jüterbog and Zossen.

In April of that year, Siemens became the director of Deutsche Bank before being commissioned as a lieutenant of the 4th Brandenburg Infantry Regiment for the Franco-German War.

From 1872 to 1874, Siemens led the establishment of Deutsche Bank in London, Paris, New York City, Argentina, Uruguay, Shanghai, and Yokohama.

The branches in Argentina, Uruguay, Shanghai, and Yokohama were later liquidated due to financial trouble.