He is not to be confused with his uncle, the banker Paul Mendelssohn-Bartholdy, who was the son of his grandfather Abraham Mendelssohn Bartholdy.
He volunteered as a soldier in the Austro-Prussian War of 1866, taking part in the Battle of Königgrätz and becoming an officer.
[1] After the Austro-Prussian War he met with Alexander Martius, a former student of Justus von Liebig, who had set up a dye factory in England.
They decided to enter a partnership to manufacture aniline in Germany, setting up a factory at the Rummelsburg Lake near Berlin.
After his death the company was led by his nephew Franz Oppenheim (1852–1929) and his son Robert Paul Hugo Mendelssohn Bartholdy (1879-1956) who had a phD in chemistry.