1111day.year
Highest Galician nobility led by Pedro Fróilaz de Traba and the bishop Diego Gelmírez crown Alfonso VII as "King of Galicia".
In 1111, Galician nobles led by Pedro Fróilaz de Traba and Bishop Diego Gelmírez crown Alfonso VII as King of Galicia, marking a key moment in the consolidation of his rule.
In the autumn of 1111, the powerful nobility of Galicia, guided by Pedro Fróilaz de Traba and Bishop Diego Gelmírez, gathered to recognize Alfonso VII as their sovereign. This coronation underscored the region's desire for autonomous leadership within the broader Iberian power struggles. Alfonso's elevation strengthened his legitimacy and expanded his influence beyond León and Castile. The ceremony reflected the complex loyalties of medieval nobility and the pivotal role of the Church. It set the stage for Alfonso's later claims to the imperial title of Hispania and reshaped alliances among Christian kingdoms in the peninsula.
1111
Galician
Pedro Fróilaz de Traba
Diego Gelmírez
Alfonso VII
1176day.year
The Battle of Myriokephalon is the last attempt by the Byzantine Empire to recover central Anatolia from the Seljuk Turks.
In 1176, the Byzantine Empire's final campaign to reclaim central Anatolia ends in defeat at the Battle of Myriokephalon against the Seljuk Turks.
The Battle of Myriokephalon on September 17, 1176, saw the forces of Emperor Manuel I Komnenos ambushed by the Seljuk Turks in the Tectorian Mountains. Despite fielding a well-trained army, the Byzantines suffered significant losses and failed to break Seljuk control over Anatolia. The defeat dashed Byzantine hopes of restoring their eastern territories and marked a turning point in the empire's decline. It highlighted the effectiveness of Turkish tactics and fortified Anatolian defenses. The battle's outcome shaped subsequent diplomatic relations and undermined Byzantine influence in the region.
1176
Battle of Myriokephalon
1382day.year
Louis the Great's daughter, Mary, is crowned "king" of Hungary.
In 1382, Mary, daughter of Louis the Great, is crowned king of Hungary, becoming one of the few female rulers to hold the title.
After the death of King Louis I, the Hungarian nobility crowned his daughter Mary as king on September 17, 1382, exercising a unique title to emphasize sovereign authority. Despite her youth, Mary inherited a kingdom facing internal factionalism and external threats. Her reign was overseen by regents, and disputes over her succession led to power struggles among noble families. Mary's ascension challenged gender norms of medieval monarchy and underscored the dynastic importance of the Angevin line. Her later marriage to Sigismund of Luxembourg would shape Central European politics for decades.
1382
Louis the Great
Mary
1462day.year
Thirteen Years' War: A Polish army under Piotr Dunin decisively defeats the Teutonic Order at the Battle of Świecino.
During the Thirteen Years' War in 1462, Piotr Dunin leads Polish forces to a decisive victory over the Teutonic Knights at Świecino.
On September 17, 1462, Polish troops commanded by Piotr Dunin confronted the Teutonic Order near the village of Świecino. Employing effective tactics and superior numbers, the Poles routed the Teutonic cavalry, inflicting heavy casualties. This victory weakened the Order's position in Pomerania and bolstered Polish claims in the region. The outcome shifted momentum in favor of King Casimir IV and laid groundwork for the eventual peace settlement. The battle remains celebrated in Polish history as a symbol of national resilience and military prowess.
1462
Thirteen Years' War
Battle of Świecino
1543day.year
The first Finnish-language book, the Abckiria by Mikael Agricola, is published in Stockholm.
In 1543, Mikael Agricola's Abckiria becomes the first book printed in Finnish, laying the foundation for the Finnish written language.
Mikael Agricola, a Finnish clergyman and scholar, published the Abckiria primer in Stockholm on September 17, 1543. Commissioned to aid literacy and religious instruction, it introduced Finnish grammar and vocabulary in written form. The work marked a milestone for Finnish culture, transforming an oral vernacular into a literary language. Agricola's efforts influenced subsequent translations of religious texts and fostered national identity. The Abckiria remains celebrated as the cornerstone of Finnish literature and linguistic development.
1543
Finnish-language
Abckiria
Mikael Agricola
Stockholm
1577day.year
The Treaty of Bergerac is signed between King Henry III of France and the Huguenots.
The 1577 Treaty of Bergerac concludes a round of the French Wars of Religion, granting limited freedoms to the Huguenots under royal authority.
Signed on September 17, 1577, the Treaty of Bergerac was negotiated by King Henry III of France and leaders of the Huguenot Protestant minority. It aimed to quell ongoing religious violence by allowing Huguenots freedom of worship in designated areas and confirming certain civil rights. Though the agreement temporarily eased tensions, ambiguities in its terms led to renewed hostilities. The treaty reflected the Crown's struggle to balance religious pluralism with centralized control. Its legacy highlights the complexities and intermittent nature of peace attempts during the Wars of Religion.
1577
Treaty of Bergerac
Henry III of France
1620day.year
Polish–Ottoman War: The Ottoman Empire defeats the Polish–Lithuanian Commonwealth during the Battle of Cecora.
In 1620, Ottoman forces defeat the Polish–Lithuanian Commonwealth at the Battle of Cecora, marking a turning point in the Polish–Ottoman War.
On September 17, 1620, troops of the Ottoman Empire clashed with the forces of the Polish–Lithuanian Commonwealth near Cecora, in present-day Romania. The battle ended in a decisive Ottoman victory, aided by tactical surprise and superior cavalry. Polish hetman Stanisław Żółkiewski was killed during a rear-guard action, dealing a blow to Commonwealth morale. The defeat opened the way for further Ottoman incursions and underscored vulnerabilities in the Commonwealth's eastern defenses. The outcome prompted subsequent diplomatic negotiations and military reforms on both sides.
1620
Polish–Ottoman War
Battle of Cecora
1631day.year
Sweden wins a major victory at the Battle of Breitenfeld against the Holy Roman Empire during the Thirty Years' War.
At the Battle of Breitenfeld in 1631, Swedish King Gustavus Adolphus secures a pivotal victory over the Holy Roman Empire during the Thirty Years' War.
The Battle of Breitenfeld, fought on September 17, 1631, marked the first major Protestant success in the Thirty Years' War. King Gustavus Adolphus of Sweden employed innovative tactics and disciplined infantry to defeat the Catholic League forces led by Count Tilly. The triumph opened central Germany to Swedish influence and galvanized Protestant states to join his cause. Gustavus Adolphus's reforms in artillery and combined arms became a model for European armies. The victory shifted the war's momentum and elevated Sweden as a great military power.
1631
Battle of Breitenfeld
Thirty Years' War
1658day.year
The Battle of Vilanova is fought between Portugal and Spain during the Portuguese Restoration War.
In 1658, Portuguese troops engage Spanish forces at the Battle of Vilanova, pressing their fight for restored independence.
The Battle of Vilanova took place on September 17, 1658, as part of the ongoing Portuguese Restoration War (1640–1668). Portuguese troops engaged Spanish invaders near Vilanova de Cerveira in a fierce encounter. Although tactically indecisive, the engagement demonstrated Portugal's resilience and bolstered national morale. Commanders on both sides tested new field tactics reflective of mid-17th-century warfare. The battle contributed to the protracted stalemate that ultimately led to Spain's recognition of Portuguese sovereignty in 1668.
1658
Battle of Vilanova
Portuguese Restoration War
1683day.year
Antonie van Leeuwenhoek writes a letter to the Royal Society describing "animalcules", later known as protozoa.
In 1683, Antoni van Leeuwenhoek reports observing microscopic 'animalcules' to the Royal Society, pioneering the study of microorganisms.
On September 17, 1683, Dutch scientist Antoni van Leeuwenhoek sent a letter to the Royal Society in London, detailing his observations of tiny living organisms under his handcrafted microscopes. He described their movements and forms, coining the term 'animalcules.' His meticulous work provided the first glimpse of the microbial world and laid foundations for microbiology. Leeuwenhoek's discoveries challenged prevailing scientific beliefs about spontaneous generation and the nature of life. His correspondence spurred interest in microscopy across Europe and advanced the scientific revolution.
1683
Antonie van Leeuwenhoek
animalcules
protozoa
1775day.year
American Revolutionary War: The invasion of Quebec by the Continental Army begins with the Siege of Fort St. Jean.
The Continental Army begins its siege of Fort St. Jean, launching an ambitious invasion of Quebec during the American Revolutionary War.
In September 1775, General Richard Montgomery led Continental forces northward from New York to strike at British-held Canada.
They laid siege to Fort St. Jean, the key defensive position guarding the Richelieu River corridor.
The campaign aimed to bring the French-speaking province of Quebec into the rebellion against British rule.
Troops faced harsh wilderness terrain, severe supply shortages, and the challenge of coordinating American and Canadian irregulars.
Despite early successes, the siege stalled as seasonal weather worsened and the garrison held firm.
Although the attempt to seize Quebec City ultimately failed, the offensive demonstrated the Colonies’ resolve and broadened the scope of the Revolutionary War.
1775
American Revolutionary War
invasion of Quebec
Continental Army
Siege of Fort St. Jean
1776day.year
The Presidio of San Francisco is founded in New Spain.
The Presidio of San Francisco is founded by Spanish colonial authorities, establishing the first permanent European settlement in the bay area.
On September 17, 1776, Spanish colonial authorities established the Presidio of San Francisco at the foot of what is now the San Francisco Peninsula.
The outpost served as a military garrison to protect Spain’s holdings in Alta California and secure the entrance to the bay.
Constructed with wooden palisades and barracks, it housed infantry forces tasked with maintaining colonial order.
Its strategic position deterred foreign threats and became a focal point for trade and settlement in the region.
Over the following decades, the Presidio evolved into a permanent settlement and administrative center.
Today, it stands as a historic park that commemorates California’s Spanish heritage.
1776
Presidio of San Francisco