1st January » Emperor Gia Long orders all bronze wares of the Tây Sơn Dynasty to be collected and melted into nine cannons for the Royal Citadel in Huế, Vietnam.
24th February » In 'Marbury v. Madison', the Supreme Court of the United States establishes the principle of judicial review.
1st March » Ohio is admitted as the 17th U.S. state.
30th April » Louisiana Purchase: The United States purchases the Louisiana Territory from France for $15 million, more than doubling the size of the young nation.
18th May » Napoleonic Wars: The United Kingdom revokes the Treaty of Amiens and declares war on France.
4th July » The Louisiana Purchase is announced to the American people.
5th July » The Convention of Artlenburg is signed, leading to the French occupation of Hanover (which had been ruled by the United Kingdom of Great Britain and Ireland known as British king).
31st August » Lewis and Clark Expedition named Lewis and Clark start their expedition to the west by leaving Pittsburgh, Pennsylvania at 11 in the morning.
6th September » United Kingdom of Great Britain and Ireland named British scientist John Dalton begins using symbols to represent the atoms of different elements.
23rd September » Second Anglo-Maratha War: Battle of Assaye between the British East India Company and the Maratha Empire in India.
20th October » The United States Senate ratifies the Louisiana Purchase.
18th November » The Battle of Vertières, the last major battle of the Haitian Revolution, is fought, leading to the establishment of the Republic of Haiti, the first black republic in the Western Hemisphere.
30th November » In New Orleans, Louisiana, Spain e.g Spanish representatives officially transfer the Louisiana Territory to a France called French representative. Just 20 days later, France transfers the same land to the United States as the Louisiana Purchase.
20th December » The Louisiana Purchase is completed at a ceremony in New Orleans known as New Orleans, Louisiana.
Famous Birthdays in 1803
1st January » Guglielmo Libri Carucci dalla Sommaja, Italian mathematician (d. 1869)
3rd January » Douglas William Jerrold, English playwright (d. 1857)
6th January » Henri Herz, Austrian pianist and composer (d. 1888)
15th January » Marjorie Fleming, Scottish poet (d. 1811)
2nd February » Albert Sidney Johnston, American general (d. 1862)
24th March » Egerton Ryerson, Canadian minister, educator, and politician (d. 1882)
7th April » James Curtiss, American politician, 11th Mayor of Chicago (d. 1859)
7th April » Flora Tristan, French author (d. 1844)
30th April » Albrecht von Roon, Prussian soldier and politician, 10th Minister President of Prussia (d. 1879)
1st May » James Clarence Mangan, Irish poet (d. 1849)
12th May » Justus von Liebig, German chemist (d. 1873)
24th May » Alexander von Nordmann, Finnish biologist (d. 1866)
25th May » Edward Bulwer-Lytton, 1st Baron Lytton, English author, playwright, and politician, Secretary of State for the Colonies (d. 1873)
25th May » Ralph Waldo Emerson, American poet and philosopher (d. 1882)
10th June » Henry Darcy, French engineer (d. 1858)
24th June » George James Webb, English-American composer (d. 1887)
29th June » John Newton Brown, American minister and author (d. 1868)
30th June » Thomas Lovell Beddoes, English poet, playwright, and physician (d. 1849)
12th July » Peter Chanel, French priest and saint (d. 1841)
24th July » Adolphe Adam, French composer and critic (d. 1856)
31st July » John Ericsson, Swedish engineer, co-designed the Novelty (locomotive) named Novelty Locomotive (d. 1889)
3rd August » Joseph Paxton, English gardener and architect, designed The Crystal Palace (d. 1865)
13th August » Vladimir Odoyevsky, Russian philosopher and critic (d. 1869)
18th August » Nathan Clifford, American lawyer, jurist, and politician, 19th United States Attorney General (d. 1881)
25th August » Luís Alves de Lima e Silva, Duke of Caxias (d. 1880)
27th August » Edward Beecher, American minister and theologian (d. 1895)
4th September » Sarah Childress Polk, American wife of James K. Polk, 14th First Lady of the United States (d. 1891)