Prosper Louis, 7th Duke of Arenberg

Prosper Louis, 7th Duke of Arenberg (28 April 1785, Enghien – 27 February 1861) was the Duke of Arenberg, a principality of the Holy Roman Empire. He was also the 13th Duke of Aarschot, 2nd Duke of Meppen and 2nd prince of Recklinghausen.

In 1801, Louis Engelbert, Duke of Arenberg, Prosper's father, lost the former Duchy of Arenberg on the left bank of the Rhine but received a larger duchy on the right bank in 1803.

In 1808 Arenberg married Stéphanie Tascher de La Pagerie a niece of Joséphine de Beauharnais (Empress of the French Empire).

His wife was given the present Hôtel de Chimay, known as the Hôtel de La Pagerie in Paris in 1808.

He was granted new lands by her husband Napoleon Bonaparte (expanding his holdings from 413 km² to 3,388 km²) and gained the additional titles of Duke of Meppen and Prince of Recklinghausen. He lost his sovereignty over his lands in 1810 when Arenberg was mediatised into France but retain the style of HSH (His Serene Highness), which is still used by his descendant.

Arenberg was colonel of the Belgian Chevau-Légers d'Arenberg which fought in the Peninsular War and was wounded captured by the British at the Battle of Arroyo dos Molinos on 28 October 1811.

Arenberg took no part in the 1815 Waterloo Campaign other than to attend the Duchess of Richmond's ball, but his contacts among the British did not save his lands which were lost when they were overrun by the Prussians and the Hanoverians. In 1816 he divorced his first wife and married again in 1819 to Princess Maria-Ludmille de Lobkowicz. Maria-Ludmille and Arenberg had seven children, the third eldest and the first boy Engelbert Auguste, inherited his father's titles becoming the 8th Duke of Arenberg.