In 1794, he entered government's service in Brunswick. In 1797 he married Elisabeth von Veltheim, who bore him four children. In 1804 he entered the government service of the Duchy of Brunswick and Lunenburg. With the establishment of the Napoleonic state in Westphalia in 1807, he entered its service. He was likely motivated in this by a desire to see reforms carried out. He did, however, oppose the French dominance of the local government, and other policies, and for his critique he was eventually arrested by orders from Louis-Nicolas Davout and imprisoned in the fortress of Gifhorn. In the same year, he lost his first wife. In the summer of 1809 Louis was appointed sub-prefect of Salzwedel, where three years later in 1812 he married Karoline Heubel; they would have three children. After Salzwedel was again under Prussian administration, in 1816 Ludwig von Westphalen was transferred to the newly established regional government in Trier.
Personal life
It was in Trier that he met and befriended Heinrich Marx, the father of Karl Marx. The children of the respective families, in particular Jenny and Edgar von Westphalen, and Sophie and Karl Marx, became close friends as well. In 1836, Jenny von Westphalen and Karl Marx became engaged; at first secretly but Ludwig approved the marriage in 1837, even though some saw Marx, who was both middle class and younger than her, as well as of Jewish descent, as an inappropriate partner for the baronial daughter. In fact, Ludwig was seen as the mentor and role model of Karl Marx, who referred to him as a "dear fatherly friend". Ludwig filled Marx with enthusiasm for the romantic school and read him Homer and Shakespeare, who remained Marx's favorite authors all his life. Marx also read Voltaire and Racine with Ludwig. Ludwig devoted much of his time to the young Marx and the two went for intellectual walks through "the hills and woods" of the neighbourhood. It was Ludwig who first introduced Marx to the personality and socialist teachings of Saint-Simon. Marx dedicated his doctoral thesis "The Difference Between the Democritean and Epicurean Philosophy of Nature" written in 1841 to Ludwig in a most effusive manner in which Marx wrote "You, my fatherly friend, have always been for me the living proof that idealism is no illusion, but the true reality" In 1842, Marx was present at the deathbed of Ludwig von Westphalen. Jenny and Karl became married in 1843, a year after Ludwig's death. He was the father of, a conservative and reactionary Prussian Minister of the Interior.
