On this day: 25 July

The Arch of Constantine is completed near the Colosseum in Rome to commemorate Constantine I's victory over Maxentius at the Milvian Bridge.

Climax of the Siege of Thessalonica by the Slavs in a three-day assault on the city walls.

The Edict of Pistres of Charles the Bald orders defensive measures against the Vikings.

Wang Geon becomes King of Goryeo after overthrowing Gung Ye in a coup the previous day.

Pope Innocent II confirms in the treaty of Mignano the investiture of the sons of Roger II of Sicily to their fiefs and abandons support for the barons opposed to Roger.

Battle of Ourique: The Almoravids, led by Ali ibn Yusuf, are defeated by Prince Afonso Henriques who is proclaimed King of Portugal.

Struggle for Constantinople: Alexios Strategopoulos led Nicaean forces to recapture Constantinople, leading to the reestablishment of the Byzantine Empire and the end of the Latin Empire.

The naval Battle of Algeciras takes place in the context of the Spanish Reconquista resulting in a victory for the Emirate of Granada and the Maranid Dynasty over the Kingdom of Castile.

The Battle of Molinella: The first battle in Italy in which firearms are used extensively.

Sebastián de Belalcázar, on his search for El Dorado, founds the city of Santiago de Cali.

The city of Guayaquil is founded by the Spanish Conquistador Francisco de Orellana and given the name Muy Noble y Muy Leal Ciudad de Santiago de Guayaquil.

The royal wedding of Mary I and Philip II of Spain is celebrated at Winchester Cathedral.

Don Diego de Losada founds the city of Santiago de Leon de Caracas, modern-day Caracas, the capital city of Venezuela.

Ignacio de Maya founds the Real Santiago de las Sabinas, now known as Sabinas Hidalgo, Nuevo León, Mexico.

At the behest of Tsar Peter the Great, the construction of Kadriorg Palace, dedicated to his wife Catherine, begins in Tallinn.

Dummer's War begins along the Maine-Massachusetts border.

American Revolutionary War: The war's last action, the Siege of Cuddalore, is ended by a preliminary peace agreement.

Mozart completed his Symphony No. 40, one of his two extant symphonies in a minor key.

The Brunswick Manifesto is issued to the population of Paris promising vengeance if the French royal family is harmed.

Napoleon Bonaparte defeats a numerically superior Ottoman army under Mustafa Pasha at the Battle of Abukir.

War of 1812: An American attack on Canada is repulsed.

Costa Rica annexes Guanacaste from Nicaragua.

American Civil War: The United States Congress passes the Crittenden–Johnson Resolution, stating that the war is being fought to preserve the Union and not to end slavery, in the wake of the defeat at the First Battle of Bull Run.

The United States Congress passes legislation authorizing the rank of General of the Army. Lieutenant General Ulysses S. Grant becomes the first to be promoted to this rank.

The Wyoming Territory is established.

The Japanese daimyōs begin returning their land holdings to the emperor as part of the Meiji Restoration reforms. (Traditional Japanese Date: June 17, 1869).

The Corinth Canal was formally opened, bisecting the narrow Isthmus of Corinth in Greece to connect the Ionian Sea's Gulf of Corinth with the Aegean Sea's Saronic Gulf.

The First Sino-Japanese War begins when the Japanese fire upon a Chinese warship.

American author Jack London embarks on a sailing trip to take part in the Klondike's gold rush, from which he wrote his first successful stories.

Ajinomoto is founded. Kikunae Ikeda of the Tokyo Imperial University discovers that a key ingredient in kombu soup stock is monosodium glutamate (MSG), and patents a process for manufacturing it.

Begin of the Tragic Week in Barcelona in response to troop mobilisations for the Rif War.

Sir Robert Borden introduces the first income tax in Canada as a "temporary" measure (lowest bracket is 4% and highest is 25%).

Telegraph Agency of the Soviet Union (TASS) is established.

General Henri Guisan orders the Swiss Army to resist German invasion and makes surrender illegal.

The Norwegian Manifesto calls for nonviolent resistance to the German occupation.

The Crossroads Baker device is the first underwater nuclear weapon test.

Korean War: After American troops withdrew, North Korean forces captured the village of Yongdong in South Korea.

The Tunisian King Muhammad VIII al-Amin is replaced by President Habib Bourguiba.

The African Regroupment Party holds its first congress in Cotonou.

Cold War: In a speech John F. Kennedy emphasizes that any attack on Berlin is an attack on NATO.

Bob Dylan goes electric at the Newport Folk Festival, signaling a major change in folk and rock music.

Vietnam War: U.S. President Richard Nixon declares the Nixon Doctrine, stating that the United States now expects its Asian allies to take care of their own military defense. This is the start of the "Vietnamization" of the war.

Soviet Mars 5 space probe is launched.

The orbiting spacecraft Viking 1 took a photograph of an apparent face on Mars in a classic example of pareidolia.

Birth of Louise Joy Brown, the first human to have been born after conception by in vitro fertilisation, or IVF.

In accord with the Egypt–Israel peace treaty, Israel begins its withdrawal from the Sinai Peninsula.

Salyut 7 cosmonaut Svetlana Savitskaya becomes the first woman to perform a space walk.

Israel and Jordan sign the Washington Declaration, that formally ends the state of war that had existed between the nations since 1948.

In a military coup in Burundi, Pierre Buyoya deposes Sylvestre Ntibantunganya.

Pratibha Patil was sworn in as the first female president of India.

WikiLeaks published 75,000 classified documents about the War in Afghanistan in one of the largest leaks in U.S. military history.

As-Suwayda attacks: Coordinated attacks occur in Syria.