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 )

* April 6 – Albert Sidney Johnston, Confederate general ( b. 1803 )

* USNA Guide to the Albert A. Michelson Collection, 1803 – 1989

These included West India Docks ( 1802 ), East India Docks ( 1803, originating from the Brunswick Dock of 1790 ), London Docks ( 1805 ), Surrey Commercial Docks ( 1807, originating from the Howland Great Wet Dock of 1696 ), St Katharine Docks ( 1828 ), Royal Victoria Dock ( 1855 ), Millwall Dock ( 1868 ), Royal Albert Dock ( 1880 ), and Tilbury docks ( 1886 ).

Nine healthy children would follow in quick succession, though two died in childhood: Crown Prince Frederick William ( 1795 ), Prince William ( 1797 ), Princess Charlotte ( 1798 ), Princess Frederica ( 1799 ), Prince Charles ( 1801 ), Princess Alexandrine ( 1803 ), Prince Ferdinand ( 1804 ), Princess Louise ( 1808 ), and Prince Albert ( 1809 ).

* Albert Lester ( c. 1803 – 1867 ), New York politician

Albert was born in Hanover and showed early talent as a musician before embarking on the study of law in Göttingen in 1803.

* Albert Sidney Johnston ( 1803 – 1862 ), career United States Army officer, Texas Army general, and Confederate States general

* Albert Smith White ( 1803 – 1864 ), Senator and U. S. Representative from Indiana

Albert Smith White ( October 24, 1803 – September 4, 1864 ) was a U. S. Senator and Representative from the state of Indiana.

Thomas Sidney Cooper ( 26 September 1803 – 7 February 1902 ) was an English landscape painter noted for his images of cattle and farm animals.

* Thomas Sidney Cooper ( 1803 – 1902 ), English painter

Other notable poets to emerge in the early and middle 19th century include Ralph Waldo Emerson, ( 1803 – 1882 ), Henry Wadsworth Longfellow ( 1807 – 1882 ), John Greenleaf Whittier ( 1807 – 1892 ), Edgar Allan Poe ( 1809 – 1849 ), Oliver Wendell Holmes ( 1809 – 1894 ), Henry David Thoreau ( 1817 – 1862 ), James Russell Lowell ( 1819 – 1891 ), and Sidney Lanier ( 1842 – 1881 ).

* 1803 – James Curtiss, American politician, Mayor of Chicago ( d. 1859 )

* 1803 – Francis Lewis, signer of the American Declaration of Independence ( b. 1713 )

Further observations were made by the German explorer Alexander von Humboldt during his South American journey from 1799 to 1803.

* Arndt, Karl J. R. George Rapp's Separatists, 1700 – 1803: The German Prelude to Rapp's American Harmony Society ; A Documentary History.

* Arndt, Karl J. R. Harmony on the Connoquenessing 1803 – 1815: George Rapp's First American Harmony.

* 1803 – The Louisiana Purchase is announced to the American people.

* 1713 – Francis Lewis, American signer of the Declaration of Independence ( d. 1803 )

* 1803 – Theodore Dwight Weld, American abolitionist ( d. 1895 )

Ralph Waldo Emerson ( May 25, 1803 – April 27, 1882 ) was an American essayist, lecturer, and poet, who led the Transcendentalist movement of the mid-19th century.

* 1722 – Samuel Adams, American politician, 4th Governor of Massachusetts ( d. 1803 )

* 1803 – Samuel Francis du Pont, American admiral ( d. 1865 )

* July 28 – Edward Beecher, American theologian ( b. 1803 )

* October 5 – William Todd ( 1803 – 1873 ), American businessman, Canadian senate nominee ( b. 1803 )

* March or April – Mercator Cooper, American sea captain ( b. 1803 )

* April 27 – Ralph Waldo Emerson, American philosopher and writer ( b. 1803 )

* July 10 – William Todd ( 1803 – 1873 ), American businessman, Canadian senate nominee

* date unknown – Samuel Mason, Revolutionary War soldier and early American outlaw ( d. 1803 )

* January 14 – Jacques-Donatien Le Ray, French supporter of the American Revolution ( d. 1803 )

* September 27 – Samuel Adams, American revolutionary leader ( d. 1803 )

* April 19 – Roger Sherman, signer of the American Declaration of Independence ( d. 1803 )

* March 21 – Francis Lewis, American signer of the Declaration of Independence ( d. 1803 )