Events of 1806

January–March

• January 1 – Kingdom of Bavaria established by Napoleon
• January 8 – Cape Colony becomes a British colony.
• January 10 – The Dutch in Cape Town surrender to the British.
• January 19 – The British occupy the Cape of Good Hope.
• January 23 – Grenville succeeds William Pitt the Younger as wartime Prime Minister of the United Kingdom, upon Pitt's death this day amidst worsening health caused by the stresses of the Napoleonic Wars
• February 6 – The Royal Navy gains a victory off Santo Domingo (see Action of 6 February 1806).
• March 23 – After traveling through the Louisiana Purchase and reaching the Pacific Ocean, explorers Lewis and Clark and their Corps of Discovery begin their journey home.
• March 29 – Construction is authorized of the National Road (the first United States federal highway).

April–June

• April 8 – Stephanie de Beauharnais, adopted daughter of Napoleon Bonaparte, marries Prince Karl Ludwig Friedrich of Baden.
• May 30 – Andrew Jackson kills a man in a duel after the man had accused Jackson's wife of bigamy.
• June 5 – Louis Bonaparte is appointed as King of Holland by his brother, Emperor Napoleon I.

July–September

• July 4 – Battle of Maida: Britain defeats France in Calabria.
• July 10 – Vellore Mutiny (the first mutiny by Indian sepoys against the British East India Company).
• July 15 – Pike expedition: Near St. Louis, Missouri, United States Army Lieutenant Zebulon Pike leads an expedition from Fort Belle Fountaine to explore the west.
• August 6 – Francis II, the last Holy Roman Emperor, abdicates, thus ending the Holy Roman Empire.
• September – Prussia declares war on France, and is joined by Saxony and other minor German states.
• September 23 – The Lewis and Clark Expedition reaches St. Louis, Missouri, ending a successful exploration of the Louisiana Territory and the Pacific Northwest.

October–December

• October 14 – Battle of Jena-Auerstädt: Napoleon defeats the Prussian army of Prince Hohenlohe at Jena while Marshal Davout defeats the main Prussian army under the Duke of Brunswick, who is killed.
• October 19 – Emperor Jacques I of Haiti (Jean-Jacques Dessalines) is assassinated at the Pont-Rouge Haiti.
• October 24 – French forces enter Berlin.
• November – Napoleon declares a Continental Blockade against the British.
• November 15 – Pike expedition: During his second exploratory expedition, Lieutenant Zebulon Pike sees a distant mountain peak while near the Colorado foothills of the Rocky Mountains (later named Pikes Peak in his honor).
• November 24 – The last major Prussian field force, under Gebhard Leberecht von Blücher, surrenders to the French near Lübeck. Frederick William III has by this time fled to Russia.
• November 30 – Napoleon captures Warsaw.
• December 26 – 1806 Battles of Pultusk and Golymin. Battle of Pultusk: Russian forces under General Bennigsen narrowly escape from a direct confrontation with Napoleon, who goes into winter quarters. Battle of Golymin: Russian forces under General Golitsyn fight a successful rearguard action against French forces under Marshall Murat.
• Noah Webster publishes his first American English dictionary.

• Thomas Bruce, 7th Earl of Elgin, removes the Elgin Marbles from the Parthenon in Athens.
• Annual British iron production reaches 260,000 tons.

Ongoing events

• Napoleonic Wars (1799–1815) – Fourth Coalition
• Russo-Turkish War, 1806-1812

Births

• January 27 – Juan Crisóstomo Arriaga, Spanish composer (d. 1826)
• February 22 – Józef Kremer, Polish messianic philosopher (d. 1875)
• March 6 – Elizabeth Barrett Browning, English poet (d. 1861)
• March 12 – Jane Pierce, First Lady of the United States (d. 1863)
• March 21 – Benito Juárez, Mexican statesman and folk hero (d. 1872)
• April 3 – Ivan Kireevsky, Russian literary critic and philosopher (d. 1856)
• April 6 – Friedrich Wilhelm Ritschl, German scholar (d. 1876)
• April 9 – Isambard Kingdom Brunel, British engineer (d. 1859)
• May 2 – Catherine Labouré, French visionary and saint (d. 1876)
• May 20 – John Stuart Mill, British philosopher (d. 1873)
• June 12 – John Augustus Roebling, German-born engineer (d. 1869)
• June 28 – Napoleon Coste, French guitarist and composer (d. 1883)
• July 5 – James Dawson, Aboriginal Guardian (d. 1900)
• October 3 – Oliver Cowdery, American religious leader (d. 1850)
• December 11 – Otto Wilhelm Hermann von Abich, German geologist (d. 1886)

Deaths

• January 23 – William Pitt the Younger, Prime Minister of the United Kingdom (b. 1759)
• February 2 – Rétif de la Bretonne, French writer (b. 1734)
• February 16 – Franz von Weyrother, Austrian general (b. 1755)
• February 19 – Elizabeth Carter, English writer (b. 1717)
• February 20 – Lachlan McIntosh, Scottish-born American military and political leader (b. 1725)
• March 23 – George Pinto English composer (b. 1785)
• March 30 – Gergiana Spencer Duchess of Devonshire (b. 1757)
• April 9 – William V of Orange (b. 1748)
• April 22 – Pierre-Charles Villeneuve, French admiral (stabbed) (b. 1763)
• May 24 – John Campbell, 5th Duke of Argyll, British field marshal (b. 1723)
• June 23 – Mathurin Jacques Brisson, French naturalist (b. 1723)
• July 10 – George Stubbs, English painter (b. 1724)
• July 11 – James Smith, American signer of the United States Declaration of Independence
• August 10 – Michael Haydn, Austrian composer (b. 1737)
• August 22 – Jean-Honoré Fragonard, French painter (b. 1742)
• August 23 – Charles-Augustin de Coulomb, French physicist (b. 1736)
• September 9 – William Paterson, signer of the United States Constitution, Governor of New Jersey (b. 1745)
• October 9 – Benjamin Banneker, American astronomer and surveyor (b. 1731)
• October 10 – Louis Ferdinand of Prussia, German prince (killed in battle) (b. 1772)
• October 25 – Henry Knox, Secretary of State under George Washington
• November 23 – Roger Newdigate, British politician (b. 1719)
• December 22 – William Vernon, American merchant (b. 1719)
• date unknown – Mungo Park, Scottish explorer (b. 1771)