Albert Sidney Johnston ( February 2, 1803 – April 6, 1862 ) served as a general in three different armies: the Texas Army, the United States Army, and the Confederate States Army.

* 1803 – Louisiana Purchase: The United States purchases the Louisiana Territory from France for $ 15 million, more than doubling the size of the young nation.

* 1803 – Albrecht von Roon, Prussian soldier and statesman, 10th Prime Minister of Prussia ( d. 1879 )

* 1803 – Edward Beecher, American theologian ( d. 1895 )

* 1803 – Vladimir Odoevsky, Russian philosopher and writer ( d. 1869 )

In the mid-19th century important leaders included Transcendentalists such as Ralph Waldo Emerson ( 1803 – 1882 ) and Henry David Thoreau ( 1817 – 1862 ).

* 1803 – Joseph Paxton, English gardener and architect, designed The Crystal Palace ( d. 1865 )

* 1803 – Thousands of meteor fragments fall from the skies of L ' Aigle, France ; the event convinces European science that meteors exist.

* 1736 – Johann Christoph Kellner, German organist and composer ( d. 1803 )

* 1744 – Johann Gottfried Herder, German writer ( d. 1803 )

* 1803 – Luís Alves de Lima e Silva, Duke of Caxias, Brazilian military commander ( d. 1880 )

The Captainship General of Cuba, encompassing Cuba and the governorships of Florida ( safe the English occupation between 1763 – 83 ), Santo Domingo ( until 1795 ), Puerto Rico, and the entire Louisiana Territory ( 1763 – 1803 )

* 1803 – Lewis and Clark start their expedition to the west by leaving Pittsburgh, Pennsylvania at 11 in the morning.

* 1719 – Johann Wilhelm Ludwig Gleim, German poet ( d. 1803 )

* 1724 – Giovanni Battista Casti, Italian poet and author ( d. 1803 )

* 1882 – Ralph Waldo Emerson, American essayist ( b. 1803 )

* 1721 – Granville Leveson-Gower, 1st Marquess of Stafford, English politician ( d. 1803 )

During the Helvetic Republic ( 1798 – 1803 ), the county of Baden, the Freie Ämter and the region known as the Kelleramt were combined into the Canton of Baden.

** 1802 – 1803 Johann Heinrich Rothpletz ( b. 1766 – d. 1833 )

** 10 March 1803 – 26 April 1803 Johann Rudolf Dolder ( b. 1753 – d. 1807 )

In 1806, Thomas Bruce, 7th Earl of Elgin, ambassador to the Ottoman Empire from 1799 to 1803 removed the large collection of marble sculptures from the Parthenon, on the Acropolis in Athens and transferred them to the UK.

Thomas Young's sketch of two-slit diffraction, which he presented to the Royal Society in 1803

Thomas Young performed a celebrated experiment in 1803 demonstrating interference from two closely spaced slits.

In 1803, Irish poet Thomas Moore arrived in Bermuda, having been appointed registrar to the Admiralty there.

He was the eldest of four surviving children ; his younger siblings were George ( 1797 – 1841 ), Thomas ( 1799 – 1818 ), and Frances Mary " Fanny " ( 1803 – 1889 ).

In 1803, President Thomas Jefferson commissioned the Corps of Discovery, and named U. S. Army Captain Meriwether Lewis its leader, who selected William Clark as his partner.

In 1803 in the midst of the Napoleonic wars between France and Britain, Thomas Jefferson authorized the Louisiana Purchase, a major land acquisition from France that doubled the size of the United States.

The presidential authority to commission officers would have a large impact on the 1803 case Marbury v. Madison, where outgoing Federalist President John Adams feverishly signed many commissions to the judiciary on his final day in office, hoping to, as incoming Democratic-Republican President Thomas Jefferson put it, " into the judiciary as a stronghold.

Thomas Young's sketch of two-slit diffraction of waves, 1803

* Thomas Stock ( 1750 – 1803 ), English clergyman

Clay and his wife had eleven children ( six daughters and five sons ): Henrietta ( 1800 – 1801 ), Theodore ( 1802 – 1870 ), Thomas ( 1803 – 1871 ), Susan ( 1805 – 1825 ), Anne ( 1807 – 1835 ), Lucretia ( 1809 – 1823 ), Henry, Jr .( 1811 – 1847 ), Eliza ( 1813 – 1825 ), Laura ( 1815 – 1817 ), James Brown ( 1817 – 1864 ), and John ( 1821 – 1887 ).

In 1803, President Thomas Jefferson issued the following instructions to Meriwether Lewis: " The object of your mission is to explore the Missouri river, & such principal stream of it, as, by its course & communication with the waters of the Pacific Ocean, whether the Columbia, Oregon, Colorado and / or other river may offer the most direct & practicable water communication across this continent, for the purposes of commerce.

In 1803 President Thomas Jefferson obtained from France the Louisiana Purchase for fifteen million dollars ( equivalent to about $ 230 million today ) which included all the land drained by the Missouri River and roughly doubled the size of U. S. territory.

Thomas Percival was a British physician who published a book called Medical Ethics in 1803.

In a famous letter to Meriwether Lewis in 1803, Thomas Jefferson instructed the Lewis and Clark expedition to " carry with you some matter of the kine-pox ; inform those of them with whom you may be, of its efficacy as a preservative from the smallpox ; & encourage them in the use of it ..." Jefferson had developed an interest in protecting Native Americans from smallpox having been aware of epidemics along the Missouri River during the previous century.

This is how Thomas Young speaking on November 24, 1803, to the Royal Society of London, began his description of the historic experiment.

After the Louisiana Purchase in 1803, President Thomas Jefferson and his successors viewed much of the land west of the Mississippi River as a place to resettle the native Americans, so that white settlers would be free to live in the lands east of the river.

* 1803 — Thomas Young develops the Double-slit experiment and demonstrates the effect of interference.

In 1803 as he was set to leave Rome, he received the commission to execute the Jason in marble from Thomas Hope, a wealthy English art-patron.

Houdon's subjects include Denis Diderot ( 1771 ), Benjamin Franklin ( 1778-09 ), Jean-Jacques Rousseau ( 1778 ), Voltaire ( 1781 ), Molière ( 1781 ), George Washington ( 1785 – 88 ), Thomas Jefferson ( 1789 ), Louis XVI ( 1790 ), Robert Fulton, 1803 – 04, and Napoléon Bonaparte ( 1806 ).

With the Louisiana Purchase in 1803, which doubled the size of the United States, Thomas Jefferson set the stage for the continental expansion of the United States.

In 1803, the Louisiana Purchase by Thomas Jefferson brought the area under United States control.

In 1803, Thomas Hopper was the first to settle in this county near Hardinsburg.

On 21 October 1803, co-founder and leader of the United Irishmen, Thomas Russell, " the man from God knows where ", was hanged outside Downpatrick Gaol for his part in Robert Emmet's failed rebellion of the same year.