Editing 1863 (section)

===April===	
* [[April 13]] – The [[Winged Victory of Samothrace]], one of the most significant sculptures of classical antiquity, is found in excavations on the Greek island of [[Samothrace]] by Charles Champoiseau. Made c.[[190 BC]], it is shipped to the [[Louvre]] in Paris.
* [[April 14]] &ndash; The [[Treaty of Huế (1863)|Treaty of Huế]] is signed between [[Vietnam]] and the [[French colonial empire|French Empire]].
* [[April 17]]&ndash;[[May 2]] &ndash; [[American Civil War]]: [[Grierson's Raid]] &ndash; [[Union (American Civil War)|Union]] cavalrymen are ambushed while crossing the [[Tickfaw River]] in [[Mississippi]].
* [[April 20]]
** American Civil War: The [[Battle of Washington]] ends inconclusively in [[Beaufort County, North Carolina]].
** The [[Augustus of Prima Porta]], one of the most significant sculptures of classical antiquity, is found in excavations in the [[Villa of Livia]] at [[Prima Porta]], near Rome.
* [[April 21]]
** {{Lang|ar-Latn|Ayyam-i butun}}: [[Bahá'u'lláh]] begins a 12-day stay in the [[Garden of Ridván, Baghdad|Najibiyyih gardens, Baghdad]] (later known as the Garden of Ridván) during which he declares his station as ''[[He whom God shall make manifest]]''. This date is celebrated in the [[Baháʼí Faith]] as the festival of [[Ridván]].<ref>{{cite encyclopedia|last=Smith|first=Peter|encyclopedia=A concise encyclopedia of the Bahá'í Faith|title=Ridvan|year=2000|publisher=Oneworld Publications|location=Oxford|pages=[https://archive.org/details/conciseencyclope0000smit/page/296 296–297]|isbn=1-85168-184-1|url=https://archive.org/details/conciseencyclope0000smit/page/296}}</ref>
** [[January Uprising]]: The Polish peasant army, now led by Zygmunt Sierakowski, achieves its first victory over the Russian army, near [[Raguva]].
* [[April 24]] &ndash; The [[Lieber Code]] signed and issued by President [[Abraham Lincoln]] to the [[Union (American Civil War)|Union]] forces of the United States in the American Civil War constitutes the world's first official comprehensive code of the modern [[laws of war]].
* [[April 30]] &ndash; [[Battle of Camarón]] in Mexico: 65 soldiers of the [[French Foreign Legion]] fight 2,000 Mexicans.