[6] So, Ludwik Pac inherited several estates, including that of Dowspuda, which was part of Užnemunė, the lands of the Grand Duchy of Lithuania that were annexed by the Kingdom of Prussia in 1795 during the Third Partition of Polish–Lithuania.

[8] In 1806, Ludwik Michał Pac served as a volunteer, equipped at his own expense, in a Polish light cavalry squadron that was part of Napoleon's Imperial Guard.

[1] During it, Pac distinguished himself militarily, demonstrating courage and military capability, while being the Chief of Staff of Marshal Jean-Baptiste Bessières' I Corps.

[2][9] For example, while commanding a squadron during the Battle of Medina de Rioseco, his horse was killed under him and he was wounded in the thigh by a bayonet thrust but he resumed the assault and pushed the enemy back.

[9] On 14 August 1808, Count Pac received the Knight's Cross of the Legion of Honour and was promoted to lieutenant colonel.

[9] On 14 July, during the celebration of the reunification of the two nations, Poland and Lithuania, at the Vilnius Cathedral, Count Pac is on Napoleon's left.

[9] In the evening, the count gives a grand ball in another of his palaces (now located at Didžioji Street 7) in which the civil and military authorities, both Lithuanian and French, partook.

[10] At Smarhon', Napoleon leaves the Grande Armée on 5 December under the guard of Pac's uhlans to reach Paris as soon as possible due to the Malet coup of 1812.

[10] Distinguishing himself by his bravery and his efficiency in staff work, Pac was elevated to the rank of commander of the Legion of Honor on 24 October 1813.

[1][10] As part of Marshal Michel Ney's army corps, Pac's regiments fought in the Campaign of France.

[10] In March, General Pac distinguished himself at the Battle of Berry-au-Bac where he defeated an enemy twice as numerous, taking nearly 300 men prisoner (including Prince Gagarin) and twice that number in horses.

[10] In the Battle of Laon, Pac was wounded in the hand and in the face, which did not prevent him from charging, taking hundreds of Russian prisoners.

[10] On 30 March 1814, Count Pac, faithful to the French emperor till the very end, personally led a charge of four squadrons with his arm still in a sling on La Villette's plateau, in front Pantin's barrier.

[10] The Grand Duke Konstantin Pavlovich of Russia order Count Pac to unite the Polish and Lithuanian troops in the plain of Saint-Denis.

[12] Pac's name figures in a plaque of the Strasbourg officers' mess called Generaux Strasbourgeois, with 1780 marked as his year of birth.