| 18 June 1155 | Holy Roman Empire, Papal States, Italy [administration] | King Frederick I Barbarossa of Germany and Italy captures and executes as a heretic Arnold of Brescia, the antipapal leader of the Roman commune, and is crowned as Holy Roman Emperor (sacrum Romanum imperator) by Pope Adrian IV, the first emperor to use the full title. |
| 18 June 1538 | France, Holy Roman Empire, Italy, Papal States, Swiss Confederation [Habsburg–Valois Wars (1494–1559)] | King Francis I of France and the Holy Roman Emperor Charles V sign the ten-year Truce of Nice; they retain their conquests in Piedmont, Italy, the Duke of Savoy losing all his territories except Nice, France; Francis recovers Hesdin and gains Mirandola in the Romagna; the Swiss Confederation retains the canton of the Vaud. |
| 18 June 1639 | UK [wars] | Due to a lack of funds, King Charles I of Great Britain and Ireland is unable to attack the Scots. He signs the Pacification of Berwick, which ends the First Bishops' War, and returns to London, England. Under the terms of the agreement, Charles agrees to refer ecclesiastical affairs to a General Assembly and civil affairs to a Parliament (which is summoned for August) and to confirm the abolition of episcopacy (rule by bishops). |
| 18 June 1757 | Prussia, Bohemia, Holy Roman Empire, Habsburg Monarchy [Seven Years War (1754–62)] | The forces of the Holy Roman Emperor Francis I defeat King Frederick II the Great of Prussia at Kolin in Bohemia; Frederick loses 13,000 of his 33,000 troops. |
| 18 June 1815 | France, UK, Belgium, Prussia, Netherlands [Napoleonic Wars (1803–15)] | Napoleon I of France, having pursued the Anglo-Dutch army of Arthur Wellesley, Duke of Wellington, engages it in the decisive Battle of Waterloo, near the Belgian village of that name, south of Brussels. Wellington manages to hold back the French attack until the Prussian army under General Gebhard von Blücher, having avoided pursuit by a French detachment under Marshal Emmanuel de Grouchy, begins to arrive in the late afternoon. As the Prussians begin to attack the French right flank, Wellington orders a counterattack, forcing the French into a retreat which soon turns into a rout. |
| 18 June 1823 | Portugal [political events] | King John VI annuls the Portuguese constitution of 1822 after risings against his rule and against the loss of Brazil. |
| 18 June 1837 | Spain [law and government] | A progressive constitution is proclaimed in Spain providing for national sovereignty, a representative house of two chambers, the absolute veto of the crown over legislation, and restricted suffrage. |
| 18 June 1887 | Germany, Russian Empire [treaties] | A secret German–Russian Reinsurance Treaty is signed to replace the expiring Three Emperors' Alliance (including Austria-Hungary), which Russia refuses to renew. |
| 18 June 1890 | Germany, Russian Empire [treaties] | Germany allows the lapse of former chancellor Otto von Bismarck's Reinsurance Treaty with Russia of June 1887, despite Russian attempts to open negotiations for a renewal. |
| 18 June–13 July 1917 | Russian Empire [World War I (1914–18)] | The Russian minister of war, Alexander Kerensky, launches the Kerensky Offensive on the Eastern Front with a series of attacks against the German armies, which are quickly repulsed with heavy Russian losses. |
| 18 June 1928 | [births and deaths] | Roald Amundsen, Norwegian explorer who was the first person to reach the South Pole, dies in the Arctic Ocean sometime after this date (he disappeared on this day; the exact date of his death is not known), while trying to rescue the Italian explorer Umberto Nobile (55). |
| 18 June 1935 | UK, Germany [diplomacy] | Britain and Germany make an agreement by which Germany undertakes that its navy will not exceed a third of the tonnage of Britain's Royal Navy. Britain's independent negotiation of the agreement fatally undermines the unity of the Stresa Front (formed in April 1935). |
| 18 June 1953 | Egypt [administration] | A republic is proclaimed in Egypt, with General Muhammad Naguib Bey as president and prime minister, and Colonel Gamal Abdel Nasser as deputy prime minister and minister of the interior. |
| 18–24 June 1983 | USA [space exploration] | The US Challenger mission (launched 18 June) includes Sally Ride, the first US woman to go into space. |
| 18 June 1996 | Israel [political events] | Binyamin Netanyahu of the Likud Party forms a government in Israel, following the defeat of the Labour Party in elections. |
| 18 June 1999 | Germany [economic conditions] | The Group of Seven (G7) industrialized nations unveils a $100 billion package of debt relief for developing countries, at the end of a three-day economic summit in Cologne, Germany. |
| 18 June 2006 | USA [Protestantism] | Conservative opposition to women clergy in the worldwide Anglican communion resurfaces as the US Episcopal Church elects Katharine Jefferts Schori to be its next presiding bishop and first woman leader. |
