The 9th Light Infantry Regiment (9e régiment d’infanterie légère) was a French army regiment.
 One of the most notable infantry regiments in the Napoleonic Wars, it was awarded the title "Incomparable" by Napoleon Bonaparte after their brilliant performance at the Battle of Marengo on 14 June 1800.
 The regiment went on to serve with distinction in the [Ulm Campaign], at the Battle of Dürenstein (11 November 1805), the Jena Campaign (1806), and the Battle of Friedland (14 June 1807).
 The regiment then served in the Peninsular War taking a notable role at the Battle of Talavera 27–28 July 1809 and the Siege of Badajoz (1812).
 Battalions from the regiment also fought on the Wagram Campaign (1809), at the Battle of Leipzig (16–19 October 1813), and Napoleon’s campaigns in France (1814).
 During the Hundred Days the 9th Light fought at Battle of Ligny (16 June 1815) and the Battle of Wavre (18–19 June 1815).
 The regiment was disbanded in the aftermath of the Bourbon Restoration.
Baron François-Xavier Donzelot (7 January 1764, Mamirolle – 11 June 1843) was a French general and a Governor of the Ionian Islands and Martinique.
 He was the son of François Donzelot and Jeanne–Baptiste Maire and had a brother named Joseph.
 He became a general of the French army in March 1801.
 Months later, he signed the surrender of Egypt to British forces.
 He then returned to France where he served in various high-echelon positions in Napoleon's army.
 Subsequently, he was appointed to serve as the head of the French garrison in Corfu and the Ionian Islands from 1807 to 1814.
 As governor, he resided in Corfu, where his gentle demeanour and mild manners made him popular with the Corfiotes.
 In 1808, he was named Baron of the Empire.
 In 1815, he was a divisional commander of Napoleon's forces at the Battle of Waterloo, during the 100-day return of Napoleon.
 After the defeat at Waterloo, he lost his position and did not work until 1817 when he was appointed governor of Martinique.
George Jones (February 25, 1766November 13, 1838) was a United States Senator from Georgia.
 Born in Savannah, he received an academic training, studied medicine with his father, and practiced for a number of years.
 He participated in the American Revolutionary War.
 He was captured by the British Army as a prisoner of war and during 1780 and 1781 was imprisoned upon an English ship.
 He was later a member of the Georgia House of Representatives and Georgia Senate, and during the War of 1812 he served as captain of a company of Savannah reserves.
 He was a member of the Savannah board of aldermen in 1793–1794, 1802–1803, and 1814–1815, and was mayor of Savannah from 1812 to 1814.
 He was appointed judge of the eastern judicial circuit of Georgia in 1804, and served until he became a U.S. Senator, appointed to fill the vacancy caused by the death of Abraham Baldwin and serving from August 27, 1807, to November 7, 1807, when a successor was elected.
Antoine Maurin (19 December 1771 – 4 October 1830) commanded a French cavalry division in 1814 during the Napoleonic Wars and in 1815 led his troops against the Prussians at Ligny where he was wounded.
 His army service began in 1792 during the French Revolution when he enlisted in a cavalry regiment as a trooper.
 He spent his entire military career as a cavalryman.
 During the French Revolutionary Wars he advanced through the ranks and became commander of a light cavalry regiment in 1802.
 While only a colonel, he commanded a brigade at Caldiero in October 1805.
 He fought in the Friedland campaign in 1807 and attained the rank of general officer that year.
 As a cavalry brigadier, he participated in the 1807 Invasion of Portugal but was captured in 1808 and held until 1812.
 He led a brigade in 1813 and a division 1814 during the War of the Sixth Coalition.
 After fighting for Napoleon during the Hundred Days, he retired in 1823.
 His surname is one of the names inscribed under the Arc de Triomphe.
The Peninsular War (1807–1814) was a military conflict between Napoleon's empire and the allied powers of Spain, Britain and Portugal, for control of the Iberian Peninsula during the Napoleonic Wars.
 The war started when French and Spanish armies invaded and occupied Portugal in 1807, and escalated in 1808 when France turned on Spain, previously its ally.
 The war on the peninsula lasted until the Sixth Coalition defeated Napoleon in 1814, and is regarded as one of the first wars of national liberation, significant for the emergence of large-scale guerrilla warfare.
Ferdinand August von Hügel (11 September 1775 – 19 October 1834) was a general in the royal Württemberg Infantry, Inspector of the Infantry Corps, and governor of the Residence city of Stuttgart.
 He was awarded the gold cross of Honor for his action in the military campaigns of 1815.
 He was one of three sons of Johann Andreas von Hügel, (born 1734 in Strassbourg and died in 1807), a captain in the Seven Years' War in the service of Württemberg.
 His father fought at the Battle of Höchstädt on the side of the Allied Coalition in 1800; after the Peace of Luneville, Württemberg fell under the influence of Napoleon's France and he commanded a regiment seconded to Napoleon's army.
 He and Dominique Vandamme had numerous confrontations during the 1809 campaign.
 Von Hügel objected to the ways in which Vandamme exploited and abused the Württemberg soldiers, when he commanded Napoleon's VIII Corps.
Zakhar Dmitrievich Olsufiev or Olsufiew or Olssufiev (1773 – 1835) led a Russian infantry corps during the 1814 Campaign in France.
 In 1805 he commanded a brigade at Austerlitz and in 1807 he was wounded at Eylau.
 In 1812 he commanded the 17th Division at Borodino and Vyazma.
 After being promoted to head the 9th Infantry Corps, he fought at the Katzbach and Leipzig in 1813 and at Brienne and La Rothière in 1814.
 At the Battle of Champaubert on 10 February 1814 he attempted to stop a 30,000-man army under Napoleon.
 His small corps was effectively destroyed and he became a French prisoner of war.
De Watteville's Regiment was a Swiss regiment founded by Louis de Watteville and recruited from regiments that served between 1799 and 1801 in the Austrian army but in British pay.
 The troops then signed on as mercenaries, to be paid by the British.
 They fought in the Napoleonic Wars (1803–1815), mainly around the Mediterranean, and were based in Malta and then in Egypt from 1801 to 1803, fighting in Sicily and Naples.
 The regiment fought and won the Battle of Maida, in Italy in July 1806.
 From 1811 to 1813 the unit served under Wellington in the Peninsular War in Spain, and defending Cadiz in the Siege of Cádiz.
 The regiment sailed to Canada in 1813 to fight in the War of 1812.
 The unit was retired at the end of the war and soldiers were given tracts of land in Canada.
The XI Corps of the "Grande Armée" was the name of a French military unit that existed during the Napoleonic Wars.
 In 1809 during the War of the Fifth Coalition, General of Division Auguste Marmont's Army of Dalmatia was renamed the XI Corps.
 Emperor Napoleon I held it in reserve at the Battle of Wagram.
 In 1812, the unit was reconstituted during the invasion of Russia and placed under Marshal Pierre Augereau.
 It did not fight in any battles and instead served a collection point for reserves.
 In spring 1813, it was reorganized and placed under the command of Marshal Jacques MacDonald.
 The corps fought at Lutzen, Bautzen, the Katzbach, Leipzig, and Hanau in 1813.
 Still under MacDonald, the unit fought at Bar-sur-Aube and several minor actions in 1814.
I Cavalry Corps (Grande Armée) was a French military formation that existed during the Napoleonic Wars.
 For one month in 1806–1807, Emperor Napoleon split his Reserve Cavalry Corps into the I and II Cavalry Corps.
 At that time, Marshal Joachim Murat took command of the short-lived I Cavalry Corps before resuming leadership over Napoleon's Reserve Cavalry when the experiment ended.
 The I Cavalry Corps was not recreated until 1812 for the French invasion of Russia when command was exercised by Étienne Marie Antoine Champion de Nansouty.
 The formation fought at Borodino and Tarutino.
 After being destroyed during the retreat from Russia, I Cavalry Corps was reconstituted in 1813 and Marie Victor de Fay, marquis de Latour-Maubourg was appointed to lead it.
 The corps fought at Lutzen, Bautzen, Dresden, and Leipzig.
 At Leipzig, Latour-Maubourg was seriously wounded and replaced by Jean-Pierre Doumerc who led the corps for the remainder of the War of the Sixth Coalition which ended with Napoleon's abdication in 1814.
 After Napoleon returned from exile and retook power in France in 1815, the main French army was baptised Armée du Nord.
 The army included a I Cavalry Corps led by Pierre Claude Pajol which fought at Ligny and Wavre, while one detached division fought at Waterloo.

Question: What nationality was the unit who fought in the war in the 1807 - 1814 war against Napoleon?
Answer: Swiss