He also joined the Prussian military in 1787 and participated in the War of the Fourth Coalition as a Rittmeister in the Dragoon regiment of his father, who had died in 1802.
After the Treaties of Tilsit and resultant army downsizing, he left the force as a captain.
Although he declined the office of Foreign Minister in 1831, he held this position from 1837 to 1841, including during the ascension of Frederick William IV.
[2] Although he had difficulties in holding his ground in domestic politics, he managed to maintain a good relationship with France, and the construction of the railway from Cologne to Antwerp was also something he promoted.
In the Oriental Crisis of 1840 Werther opposed the Russian pressure for Prussia to engage herself militarily, as he was of the opinion that in a potential war, due to Austria's military weakness the main burden would fall on Prussia.