| 8 August 480 BC | Greece [Greek–Persian War (490 BC)] | A small force under King Leonidas of Sparta holds the invading Persian land force at the pass of Thermopylae (leading from Thessaly to Phocis in central Greece), inflicting heavy casualties on them. The Spartans are wiped out but their bravery becomes almost legendary. |
| 8 August 843 | Carolingian Empire [treaties] | The Treaty of Verdun settles the quarrels of the heirs of the late Frankish emperor Louis I the Pious over their inheritance. Lothair I retains the title of emperor and receives ‘the Middle Kingdom’ (Italy, lands between the Rhine and Rhône–Saône–Scheldt, and Frisia, including the imperial capitals Rome and Aachen), while Louis the German receives the East Frankish Kingdom (Saxony, Franconia, Swabia, Bavaria, and Carinthia) and Charles II the Bald receives the West Frankish Kingdom (Neustria, Aquitaine, Gascony, and the Spanish March). |
| 8 August 1059 | Italy, Apulia, Sicily, Byzantine Empire [wars] | In the Treaty of Melfi, Pope Nicholas II invests Robert Guiscard as his vassal, proclaiming him Duke of Apulia and Calabria and Count of Sicily. These territories are still largely occupied by the Byzantines and the Arabs but the Pope's grant legitimizes Guiscard's campaigns to conquer them. |
| 8 August 1107 | England [Catholicism] | King Henry I of England and Anselm, archbishop of Canterbury, settle their disagreement over the investiture of bishops at the synod of Westminster: Henry agrees to end lay investiture (investiture by a lay ruler). |
| 8 August 1124 | Holy Roman Empire, France, England [wars] | Emperor Henry V of Germany attempts to invade France as the ally of King Henry I of England, but retires as the French vassals respond to King Louis VI of France's summons to military service. Louis's success in exercising his feudal rights marks a major advance in the authority of the French monarchy. |
| 8 August 1135 | Poland, Bohemia, Holy Roman Empire, Hungary [diplomacy] | Emperor Lothair III makes peace between Poland and Bohemia, receiving homage from Boleslaw III, Duke of Poland; he also settles a dispute over the succession to the Hungarian crown. |
| 8 August 1191 | Holy Roman Empire, Italy, Germany [wars] | Empress Constance is captured in a revolt in Salerno, Italy, while the Holy Roman Emperor Henry VI is forced by fever in his army to raise the siege of Naples and return to Germany. |
| 8 August 1219 | Egypt, France, Germany, Hungary, Spain [Christianity] | St Francis preaches to the sultan and to the crusaders in Egypt. Missions of his friars are sent to France, Germany, Hungary, and Spain. |
| 8 August 1221 | Ayyubid Sultanate, Egypt, Italy, Scandinavia, Austria, Germany, Flanders [Crusades (1095–1272)] | The army of the Fifth Crusade, advancing into Egypt from Damietta, is trapped by the Nile floods and the Egyptian army; the leader of the crusade, Cardinal Pelagius, is forced to accept Sultan al-Kamil of Egypt's terms for withdrawal, including the surrender of Damietta. |
| 8 August 1233 | Wales, England [wars] | Richard the Marshal, Earl of Pembroke, in alliance with Llywelyn ap Iorwerth the Great, Prince of Gwynedd (north Wales), begins a revolt against King Henry III of England. |
| 8 August 1246 | Mongol Empire [political events] | Guyuk, son of the late Great Khan Ogedai, is elected great khan of the Mongols; he receives Pope Innocent IV's envoy. |
| 8 August 1296 | England, Scotland [Anglo–Scottish Wars 1296–1371)] | King Edward I of England returns from Scotland, bringing ‘the Stone of Destiny’, on which Scottish kings are crowned, as a symbol of his conquest of Scotland, from Scone to Westminster Abbey, London, England. |
| 8 August 1300 | Holy Roman Empire [wars] | The Holy Roman Emperor Albert I abandons his siege of Nijmegen in the war against John of Hainault. This failure is followed by a revolt of the Rhenish princes. |
| 8 August 1307 | Scotland, England [Anglo–Scottish Wars 1296–1371)] | King Edward II of England campaigns in Scotland, briefly. On his withdrawal Robert I the Bruce, King of Scotland, re-establishes himself. |
| 8 August 1324 | France, England [wars] | King Charles IV of France invades Gascony when the parliament of Paris declares the province confiscated because King Edward II of England's lieutenant has sacked the French fortified town of Saint-Sardos. |
| 8 August 1352 | France, England [Hundred Years War (1337–1453)] | The English forces in Brittany defeat the Montfort faction at Mauron, Brittany, ending the dispute over the occupancy of the duchy of Brittany. |
| 8 August 1471 | Netherlands [births and deaths] | Thomas à Kempis (original name Thomas Hemerken), theologian to whom the highly influential De imitatione Christi/On the Imitation of Christ is attributed, dies in Agnietenberg, near Zwolle, Netherlands (c. 92). |
| 8 August 1553 | England [Catholicism] | With the accession of Mary I to the throne of England, Roman Catholicism is restored in England and Roman Catholic bishops are reappointed. |
| 8 August 1570 | France [treaties] | By the Peace of St Germain, the concessions to the Huguenots (French Protestants) of the treaties of Amboise (1563) and Longjumeau (1568) are restored; an amnesty is granted and the Huguenots gain the French strongholds of La Rochelle, Montauban, Cognac, and La Charité as places of refuge. Catherine de' Medici, the queen mother, reverses her alliances, supporting the Huguenot admiral Gaspard de Coligny against Guise influence. |
| 8 August 1648 | Ottoman Empire [political events] | The Ottoman sultan Ibrahim is deposed in a revolt by the Janissaries (infantry) and Ulama (religious notables). He is executed ten days later on 18 August and is succeeded by Mehmed IV. |
| 8 August 1700 | Russia, Ottoman Empire [treaties] | The Treaty of Constantinople between Russia and the Ottoman Empire converts the two-year armistice agreed at Carlowitz in January 1699 to a 30-year truce between the two powers. The Ottoman Empire cedes the fortress of Azov, captured by Tsar Peter I the Great in July 1696, and grants Russia the right to keep a permanent ambassador in Constantinople. Russian tributes to the Tatars are also waived. |
| 8 August 1829 | France [law and government] | King Charles X of France appoints Auguste, Prince de Polignac, prime minister, an ultra-conservative who does not possess the confidence of the Chamber, in a move away from responsible government. |
| 8 August 1843 | India, UK [colonization] | Britain formally annexes the Indian province of Sind (in modern-day Pakistan), having militarily subdued its inhabitants. |
| 8 August 1854 | UK, Austrian Empire, France, Russian Empire, Serbia [diplomacy] | The ‘Four Points’ issued by Britain, Austria, and France from the Austrian capital, Vienna, state their conditions of peace with Russia to be Russia's abandonment of its claim to a protectorate over the Ottoman sultan's Christian subjects, revision of the Straits settlement in the interests of European powers, free passage of the mouth of the River Danube, and a guarantee of the integrity of the Danubian principalities of Moldavia and Wallachia, and of Serbia. |
| 8 August 1875 | UK [legislation] | The Public Health Act is passed by the British Parliament, providing a complete sanitary code for both the public and industry. It lays the foundation of modern sanitary legislation in Britain. |
| 8 August 1879 | Mexico [births and deaths] | Emiliano Zapata, Mexican revolutionary who leads a guerilla force during the Mexican Revolution, born in Anenecuilo, Mexico (–1919). |
| 8–10 August 1900 | USA, UK [tennis] | The US public official Dwight Filley Davis presents an international challenge cup for lawn tennis, the Davis Cup. The USA wins the trophy, beating Britain 3–0 at Brookline, Massachusetts. |
| 8 August 1902 | [births and deaths] | Paul Adrien Maurice Dirac, English physicist, author of the complete theoretical formulation of quantum mechanics, born in Bristol, England (–1984). |
| 8 August 1903 | USA [aircraft] | US astronomer and physicist Samuel Pierpont Langley achieves the first flight of a heavier-than-air vehicle powered by a petrol engine. It is uncrewed and flies 300 m/1,000 ft in 27 seconds. |
| 8–11 August 1918 | France, United Kingdom, Germany [World War I (1914–18)] | The Battle of Amiens is fought on the Western Front, British forces breaking the German line to such an extent that 8 August becomes known as ‘the black day of the German army’. |
| 8 August 1926 | UK, France, USA [sports] | Gertrude Ederle of the USA becomes the first woman to swim the English Channel, completing the 56 km/35 mi crossing from Cape Nez, France, to Dover, England, in 14 hrs, 31 min, a new world record for a man or a woman. |
| 8 August 1962 | South Africa [crime and punishment] | The leader of the South African organization Umkonto we Sizwe (‘ Spear of the Nation’), Nelson Mandela, is arrested when returning to Johannesburg, South Africa, from Natal. He is tried in November, and convicted of inciting workers to strike and of leaving the country without valid documents. He is sentenced to five years in prison. |
| 8 August 1969 | France [banking and finance] | France devalues the franc by 12% following a European financial crisis. |
| 8 August 2000 | Chile [law and government] | The Supreme Court of Chile confirms that Augusto Pinochet no longer has parliamentary immunity, laying the former dictator open to prosecution for human rights offences during his rule. |
