Upon the dissolution of the Holy Roman Empire in 1806, the
Free Imperial City of Hamburg became a
sovereign state with the official title of the
Free and Hanseatic City of Hamburg. Hamburg was briefly annexed by
Napoleon I to the
First French Empire, but Russian forces under
General Bennigsen freed the city in 1814. Hamburg re-assumed its pre-1811 status as a city-state in 1814 when Rumpff returned to his hometown. He joined the diplomatic service and served as
attaché at the
Congress of Vienna which confirmed Hamburg's independence and it became one of 39 sovereign states of the
German Confederation. In 1815, he was sent to
Frankfurt as legation secretary of the Hamburg embassy to the
Bundestag. In 1819, he acquired Hamburg citizenship. Hamburg entrusted him with the newly founded Hanseatic embassy at the
Imperial Court in Vienna, and appointed him Minister. In 1824, he took over the post of Minister at the French court in Paris and was a representative of the
Hanseatic merchants in Paris. The other three free cities of
Bremen, Frankfurt and
Lübeck also delegated their diplomatic representation to him. From 1827 to 1828, Rumpff served as
Minister of the Hanseatic cities of Bremen, Hamburg and Lübeck to the United States. While Minister, Rumpff and his colleague
James Colquhoun in London, signed a series of commercial treaties and trade agreements, including with the United States of America in 1827 and 1828, France in 1843, Sardinia in 1844, Monaco in 1846, New Granada in 1854, and Persia in 1857. Rumpff retired in 1864 and was succeeded as Ambassador of the Hanseatic cities in Paris by
Hermann von Heeren. ==Personal life==