Maurin led a cavalry brigade in Andoche Junot's army during the 1807 Invasion of Portugal. He was named Baron of the Empire on 17 March 1808. He reported to François Étienne de Kellermann who commanded a cavalry division that included one squadron each of the 26th Chasseurs à Cheval, 1st, 3rd, 4th, 5th, 9th, and 15th Dragoons. Maurin was appointed governor of Algarve province in the south of Portugal. When the revolt against the French occupation broke out, he was in his sickbed in Faro. He and 70 other French soldiers were captured by Portuguese partisans on 16 June 1808 and handed over to the captain of a British naval vessel as prisoners.
Maurin remained a prisoner until September 1812. After his return he fought at the Battle of Dresden on 26–27 August 1813. He received the Commander's Cross of the Légion d'Honneur on 28 September 1813. Maurin commanded the 9th Light Cavalry Brigade in Rémi Joseph Isidore Exelmans' division of the II Cavalry Corps at the Battle of Leipzig on 16–19 October. The brigade included the 4th, 7th, and 20th Chasseurs à Cheval, and 6th Lancer Regiments.
On 20 February 1814, Maurin's 2nd Light Cavalry Division was part of the II Cavalry Corps and was made up of the 1st Brigade under Jean-Baptiste Dommanget and the 2nd Brigade under an officer named Jamin. The 838-strong 1st Brigade included the 5th and 9th Hussar, 11th and 12th Chasseurs à Cheval, and 2nd and 4th Lancer Regiments. The 962-man 2nd Brigade consisted of the 7th, 20th, 23rd, and 24th Chasseurs à Cheval, and 6th Lancer Regiments. Maurin led this unit at the Battle of Laubressel on 3–4 March 1814. An order of battle for 10 March notes that the division included a detachment from the 5th Horse Artillery armed with three 6-pounder guns and one howitzer, numbering 53 gunners and 53 teamsters. By this date, hard campaigning had shrunk the 1st Brigade to 606 troopers and the 2nd Brigade to 476 troopers. By 1 May 1814, Maurin's 2nd Light Cavalry Division was in the I Cavalry Corps and included the same regiments as in February.
After Napoleon's abdication Maurin submitted to King Louis XVIII of France. He later rejoined the emperor during the Hundred Days and was appointed to command the 7th Cavalry Division in the 1815 campaign. The division's 1st Brigade was led by Louis Vallin and consisted of the 6th Hussars and 8th Chasseurs à Cheval Regiments. The 2nd Brigade was under Pierre Marie Auguste Berruyer and comprised the 6th, 11th, and 18th Dragoon Regiments. At the Battle of Ligny on 16 June 1815, Maurin was wounded in the chest by a bullet. He retired in 1823. After the July Revolution of 1830 he returned to active service but died on 4 October 1830. His surname is one of the names inscribed under the Arc de Triomphe, on the west pillar.