* 1723 – Mathurin Jacques Brisson, French naturalist ( d. 1806 )

* 1806 – Francis II, the last Holy Roman Emperor, abdicates ending the Holy Roman Empire.

* 1806 – Battle of Mišar during the Serbian Revolution begins.

* 1806 – Santiago de Liniers, 1st Count of Buenos Aires re-takes the city of Buenos Aires, Argentina after the first British invasion.

* 1724 – George Stubbs, English painter ( d. 1806 )

* Anton Alexander Graf von Auersperg ( 1806 – 1876 ) – Austrian poet who wrote under the pseudonym of Anastasius Grün.

The Lewis and Clark Expedition spent the winter of 1805 – 1806 at Fort Clatsop, a small log structure south and west of modern day Astoria.

* 1806 – Michael Haydn, Austrian composer ( b. 1737 )

* 1727 – Michel Adanson, French botanist ( d. 1806 )

* William Bernard Ullathorne ( 1806 – 89 )

Following his conquest of most of Western Europe, the first Napoleon made his elder brother Joseph ( 1768 – 1844 ) king first of Naples ( 1806 – 1808 ) and then of Spain ( 1808 – 1813 ), his third brother Louis ( 1778 – 1846 ) king of Holland ( 1806 – 1810 ) ( subsequently forcing his abdication after his failure to subordinate Dutch interests to those of France ) and his youngest brother Jérôme Bonaparte ( 1784 – 1860 ) king of Westphalia, the short-lived realm created from some of the states of northwestern Germany ( 1807 – 1813 ).

Jean-Robert Argand introduced the term " module " ' unit of measure ' in French in 1806 specifically for the complex absolute value and it was borrowed into English in 1866 as the Latin equivalent " modulus ".

The term " absolute value " has been used in this sense since at least 1806 in French and 1857 in English.

In 1806, the French chemists Louis-Nicolas Vauquelin and Pierre Jean Robiquet isolated a compound in asparagus that was subsequently named asparagine, the first amino acid to be discovered.

The monument was designed by Jean Chalgrin in 1806, and its iconographic program pitted heroically nude French youths against bearded Germanic warriors in chain mail.

Clausewitz served in the Rhine Campaigns ( 1793 – 1794 ) including the Siege of Mainz, when the Prussian army invaded France during the French Revolution, and served in the Napoleonic Wars from 1806 to 1815.

* 1806 – Battles of Pultusk and Golymin: Russian forces hold French forces under Napoleon.

In the Capitulation of Erfurt the city, its 12, 000 defenders, and the Petersberg fortress were handed over to the French on 16 October 1806.

The city became part of the First French Empire in 1806 as Principality of Erfurt, and was returned to Prussia in 1815 after the Napoleonic Wars.

* 1806 – Battle of San Domingo: British naval victory against the French in the Caribbean.

The Confederation of the Rhine, a confederation of client states of the First French Empire, existed from 1806 to 1813.

A pro-French Batavian Republic was established ( 1795 – 1806 ), and with the consolidation of French power under Napoleon gradually turned into a French satellite state, culminating in the Kingdom of Holland ( 1806 – 1810 ) and later simply an imperial province.

; 2nd ed., 1806 ), which was translated into French and served as a model for Wilhelm Adolf Becker's Gallus and Charicles.

* 1806 – Catherine Labouré, French visionary and saint ( d. 1876 )

Mai 1806. jpg | In this 1806 French print, the woman with the Menorah represents the Jews being emancipated by Napoleon Bonaparte

In the course of the Napoleonic Wars, the fortress surrendered to French troops in 1806.

* 1806 – Believing he was facing a much larger force, Prussian Lieutenant General Friedrich von Romberg, commanding 5, 300 men, surrendered the city of Stettin to 800 French soldiers commanded by General Lassalle.

Much of Clausewitz's thinking was based on his experience as a Prussian war planner concerned with how to use popular forces in an insurrectionary struggle against the much-superior French forces which occupied Prussia after 1806 — how, in short, to wage a " Spanish War in Germany.

* 1806 – Christophe Léon Louis Juchault de Lamoricière, French general ( d. 1865 )

* 1806 – Pike expedition: United States Army Lieutenant Zebulon Pike begins an expedition from Fort Bellefontaine near St. Louis, Missouri, to explore the west.

After defeating Prussian forces at Battle of Jena-Auerstedt | Jena, the French Army entered Berlin on 27 October 1806

The second phase of fort-building ( 1806 – 1819 ) included Fort Pitt ( later used as a hospital and the site of the first Army Medical School ).

After defeating Prussian forces at Battle of Jena-Auerstedt | Jena, the French Army entered Berlin on 27 October 1806

Only a few Calabrians resisted the invading French force and the Royal Neapolitan Army was soundly defeated at the Battle of Campo Tenese on 10 March 1806.

In 1806 Napoleon made his decision to erect a memorial, a Temple de la Gloire de la Grande Armée (" Temple to the Glory of the Great Army "); following an elaborate competition with numerous entries and a jury that decided on a design by the architect Claude Étienne de Beaumont ( 1757 – 1811 ), the Emperor trumped all, instead commissioning Pierre-Alexandre Vignon ( 1763 – 1828 ) to build his design on an antique temple ( Compare the Maison Carrée, in Nîmes ) The then-existing foundations were razed, preserving the standing columns, and work begun anew.

As a United States Army captain in 1806 – 1807, he led the Pike Expedition to explore and document the southern portion of the Louisiana Purchase and to find the headwaters of the Red River, during which he recorded the discovery of what later was called Pikes Peak.

Major-General Sir William Ponsonby KCB ( 13 October 1772 – 18 June 1815 ), styled The Honourable from 1806, was an Irish politician and British Army officer who served in the Peninsula War and was killed at the Battle of Waterloo.

Henry Knox ( July 25, 1750 – October 25, 1806 ) was a military officer of the Continental Army and later the United States Army, and also served as the first United States Secretary of War.

* John B. Grayson ( 1806 – 1861 ), U. S. Army officer

The Corps of Discovery was a specially-established unit of the United States Army which formed the nucleus of the Lewis and Clark expedition between May 1804 and September 1806.

" On return in 1806, the expedition helped him secure an officer's commission in the U. S. Army.

* Amos Beebe Eaton ( 1806 – 1877 )— Civil War Union Army Brigadier General.

During this conflict, Soulouque became a respected soldier and as a consequence he was commissioned as a Lieutenant in the Army of Haïti in 1806 and made aide-de-camp to General Lamarre.

Zebulon Pike led a U. S. Army reconnaissance expedition into the disputed region in 1806.

In 1806, the Prussian Army was defeated by Napoleon Bonaparte at the Battle of Jena, and in the aftermath of this defeat, the Prussian Army and state largely collapsed.

He was a general in the Army as well as a prominent politician, and notably served as Foreign Secretary from 1805 to 1806 and as First Lord of the Admiralty from 1807 to 1810.

He served in Austria in 1805, in Prussia in 1806, Poland in 1807, where he distinguished himself at Eylau and Friedland, Spain in 1808, and commanded the cavalry of the Army of Italy in 1809 in the Viceroy Eugène's advance to Vienna.

* James Grant ( British Army officer ) ( 1720 – 1806 ), British general in Revolutionary War

His great-grandson, the seventeenth Lord, was a General in the Army and sat in the House of Lords as a Scottish Representative Peer from 1806 to 1843.

* George Cadwalader ( 1806 – 1879 ), American U. S. Army general during the Mexican-American War and American Civil War

John Jordan Crittenden ( 1754 – May 1806 ) was a Major in the Continental Army during the American Revolutionary War and a member of the Virginia House of Burgesses from 1790 to 1805.