| 56761 | May.18 | Event | 1565 – The Great Siege of Malta begins, in which Ottoman forces attempt and fail to conquer Malta. |
| 56762 | May.18 | Event | 1565 – The Royal Audiencia of Concepción is created by a decree of Philip II of Spain. |
| 56763 | May.18 | Event | 1593 – Playwright Thomas Kyd's accusations of heresy lead to an arrest warrant for Christopher Marlowe. |
| 56764 | May.18 | Event | 1631 – In Dorchester, Massachusetts, John Winthrop takes the oath of office and becomes the first Governor of Massachusetts. |
| 56765 | May.18 | Event | 1652 – Rhode Island passes the first law in English-speaking North America making slavery illegal. |
| 56766 | May.18 | Event | 1756 – The Seven Years' War begins when Great Britain declares war on France. |
| 56767 | May.18 | Event | 1763 – Fire destroys a large part of Montreal |
| 56768 | May.18 | Event | 1783 – First United Empire Loyalists reach Parrtown (later called Saint John, New Brunswick, Canada after leaving the United States. |
| 56769 | May.18 | Event | 1803 – Napoleonic Wars: The United Kingdom revokes the Treaty of Amiens and declares war on France. |
| 56770 | May.18 | Event | 1804 – Napoleon Bonaparte is proclaimed Emperor of the French by the French Senate. |
| 56771 | May.18 | Event | 1811 – Battle of Las Piedras: The first great military triumph of the revolution of the Río de la Plata in Uruguay led by José Artigas. |
| 56772 | May.18 | Event | 1812 – John Bellingham is found guilty and sentenced to death by hanging for the assassination of British Prime Minister Spencer Perceval. |
| 56773 | May.18 | Event | 1843 – The Disruption in Edinburgh of the Free Church of Scotland from the Church of Scotland. |
| 56774 | May.18 | Event | 1848 – Opening of the first German National Assembly (Nationalversammlung) in Frankfurt, Germany. |
| 56775 | May.18 | Event | 1860 – Abraham Lincoln wins the Republican Party presidential nomination over William H. Seward, who later becomes the United States Secretary of State. |
| 56776 | May.18 | Event | 1863 – American Civil War: The Siege of Vicksburg begins. |
| 56777 | May.18 | Event | 1896 – The United States Supreme Court rules in Plessy v. Ferguson that the "separate but equal" doctrine is constitutional. |
| 56778 | May.18 | Event | 1896 – Khodynka Tragedy: A mass panic on Khodynka Field in Moscow during the festivities of the coronation of Russian Tsar Nicholas II results in the deaths of 1,389 people. |
| 56779 | May.18 | Event | 1900 – The United Kingdom proclaims a protectorate over Tonga. |
| 56780 | May.18 | Event | 1910 – The Earth passes through the tail of Comet Halley. |
| 56781 | May.18 | Event | 1912 – The first Indian film, Shree Pundalik by Dadasaheb Torne is released in Mumbai. |
| 56782 | May.18 | Event | 1917 – World War I: The Selective Service Act of 1917 is passed, giving the President of the United States the power of conscription. |
| 56783 | May.18 | Event | 1926 – Evangelist Aimee Semple McPherson disappears while visiting a Venice, California beach. |
| 56784 | May.18 | Event | 1927 – The Bath School disaster: Forty-five people are killed by bombs planted by a disgruntled school-board member in Michigan. |
| 56785 | May.18 | Event | 1927 – After being founded for 20 years, the Government of the Republic of China approves Tongji University to be among the first national universities of the Republic of China. |
| 56786 | May.18 | Event | 1933 – New Deal: President Franklin D. Roosevelt signs an act creating the Tennessee Valley Authority. |
| 56787 | May.18 | Event | 1944 – World War II: Battle of Monte Cassino: Conclusion after seven days of the fourth battle as German paratroopers evacuate Monte Cassino. |
| 56788 | May.18 | Event | 1944 – Deportation of Crimean Tatars by the Soviet Union government. |
| 56789 | May.18 | Event | 1948 – The First Legislative Yuan of the Republic of China officially convenes in Nanking. |
| 56790 | May.18 | Event | 1953 – Jackie Cochran becomes the first woman to break the sound barrier. |