Editing 1803 (section)

=== April–June ===
* [[March]]–[[April]] – The ''[[franc germinal]]'' is introduced in France.
* [[April 5]] — [[Ludwig van Beethoven]] puts on a big Akademie concert at the [[Theater an der Wien]], in Vienna consisting of the premieres of his [[Symphony No. 2 (Beethoven) | second symphony]], [[Piano Concerto No. 3 (Beethoven)| third piano concerto]], and his oratorio [[Christ on the Mount of Olives (Beethoven)|Christ on the Mount of Olives.]]
* [[April 26]] – The [[L'Aigle (meteorite)|L'Aigle meteorite]] falls in Normandy, causing a shift in scientific opinion on the origin of meteorites.
* [[April 30]] – The [[Louisiana Purchase]] is made from France by the United States.
* [[May]] – [[Napoleon|First Consul of France, Citizen Bonaparte]], begins making [[Napoleon's planned invasion of the United Kingdom|preparations to invade England]].
* [[May 18]] – The [[Napoleonic Wars]] begin, when the United Kingdom declares war on France, after France refuses to withdraw from Dutch territory.
* [[May 19]] – [[Master Malati]], a [[Coptic Orthodox Church of Alexandria|Coptic Christian]] leader, is beheaded by a [[Muslim]] mob in [[Cairo]], Egypt.
* [[June 5]] – [[Convention of Artlenburg]] agrees a ceasefire following the [[Invasion of Hanover (1803)|French Invasion of Hanover]]. Large numbers of the former [[Hanoverian Army]] go into exile to join the [[King's German Legion]]
* [[June 7]] – [[Indiana Territory]] governor (and future U.S. president) [[William Henry Harrison]] signs [[Treaty of Fort Wayne (1803)|treaties]] at [[Fort Wayne, Indiana|Fort Wayne]], with representatives of the [[Lenape|Delaware]], [[Shawnee Tribe|Shawnee]], [[Potawatomi]], [[Miami people|Miami]], [[Kickapoo people|Kickapoo]], [[Eel River Tribe|Eel River]], [[Wea]], [[Piankeshaw]] and [[Kaskaskia]] Indian tribes. The U.S. Senate ratifies the treaties on November 25.<ref>''Laws of the United States of America; from March 4, 1789, to March 4, 1815'' (Weightman, 1815) p714</ref>
* [[June 14]] – [[Napoleon Bonaparte]] orders the establishment of five military camps to defend the coast of France, located at [[Bayonne]], [[Ghent]], [[Saint-Omer]], [[Compiègne]], [[Saint-Malo]], and one in the occupied Netherlands, at [[Utrecht]]. Each one has 20,000 infantry and 2,000 cavalry to defend it.<ref>Frederick C. Schneid, ''Napoleon's Conquest of Europe: The War of the Third Coalition'' (Greenwood, 2005) pp77-78</ref>