325day.year
The First Council of Nicaea is formally opened, starting the first ecumenical council of the Christian Church.
The First Council of Nicaea convenes under Emperor Constantine, marking the first unified gathering of Christian bishops.
Called by Constantine the Great, the Council of Nicaea assembled over 300 bishops in what is now Iznik, Turkey. The council aimed to address the Arian controversy and establish doctrinal unity in the Christian Church. Delegates debated key theological points, culminating in the formulation of the original Nicene Creed. The council also set a unified date for Easter and addressed various church canons. Its outcomes shaped Christian orthodoxy and influenced ecclesiastical governance for centuries.
325
First Council of Nicaea
ecumenical council
491day.year
Empress Ariadne marries Anastasius I. The widowed Augusta is able to choose her successor for the Byzantine throne, after Zeno (late emperor) dies of dysentery.
Empress Ariadne of Byzantium marries Anastasius I, securing the imperial succession after Zeno’s death.
Following the death of Emperor Zeno, Empress Ariadne exercised her authority as Augusta to select her new consort. She chose Anastasius, a trusted palace official, who was proclaimed emperor upon their marriage. Anastasius enacted administrative reforms, improved fiscal management, and oversaw the construction of the Anastasian Wall defending Constantinople. His reign brought stability and strengthened the eastern Roman Empire. He ruled successfully until 518, leaving a lasting imprint on Byzantine governance.
491
Ariadne
Anastasius I
Augusta
Byzantine
Zeno
dysentery
685day.year
The Battle of Dun Nechtain is fought between a Pictish army under King Bridei III and the invading Northumbrians under King Ecgfrith, who are decisively defeated.
Pictish forces under Bridei III rout King Ecgfrith’s Northumbrian army at Dun Nechtain, preserving Pictish independence.
In 685, King Ecgfrith of Northumbria led an invasion into Pictish lands but faced a crushing defeat at Dun Nechtain. Pictish warriors commanded by King Bridei III ambushed the Northumbrians near modern-day Dunnichen in Scotland. The loss halted Northumbrian expansion and secured Pictish autonomy for generations. Ecgfrith narrowly escaped capture, while many of his nobles were killed or taken prisoner. This decisive clash reshaped the power balance in early medieval Britain.
685
Battle of Dun Nechtain
Pictish
Bridei III
Northumbrians
Ecgfrith
794day.year
While visiting the royal Mercian court at Sutton Walls with a view to marrying princess Ælfthryth, King Æthelberht II of East Anglia is taken captive and beheaded.
King Æthelberht II of East Anglia is seized and executed at Sutton Walls, ending his dynasty’s ambitions.
While seeking to marry Mercian princess Ælfthryth in 794, King Æthelberht II attended the court at Sutton Walls. Instead of a royal match, he was arrested on suspicion of plotting against King Offa of Mercia. Æthelberht was beheaded, cutting short East Anglian hopes and consolidating Mercian dominance. His body was later venerated as a martyr, and his remains were reburied at Hereford Cathedral. The incident highlights the ruthless power struggles of Anglo-Saxon England.
794
Mercian
Sutton Walls
Ælfthryth
Æthelberht II of East Anglia
beheaded
1217day.year
The Second Battle of Lincoln is fought near Lincoln, England, resulting in the defeat of Prince Louis of France by William Marshal, 1st Earl of Pembroke.
William Marshal leads royalist forces to victory over Prince Louis at the Second Battle of Lincoln, tipping the balance in the First Barons’ War.
During the First Barons’ War, Prince Louis of France laid siege to Lincoln Castle in 1217. William Marshal, the 1st Earl of Pembroke, arrived with loyalist troops and launched a surprise attack. Marshal’s cavalry charge broke the French-backed forces, resulting in heavy casualties and the capture of key commanders. The victory ended Louis’s campaign and strengthened King Henry III’s claim to the throne. Marshal’s reputation as a masterful commander was cemented, bringing renewed stability to England.
1217
Second Battle of Lincoln
Lincoln
Prince Louis of France
William Marshal, 1st Earl of Pembroke
1293day.year
King Sancho IV of Castile creates the Estudio de Escuelas de Generales in Alcalá de Henares.
King Sancho IV of Castile founds the Estudio de Escuelas de Generales in Alcalá de Henares, an early center for higher learning.
In 1293, Sancho IV established the Estudio de Escuelas de Generales to formalize advanced education in Castile. Located in Alcalá de Henares, it offered studies in theology, canon law, and the liberal arts. The school attracted prominent scholars and emphasized rigorous instruction in Latin grammar. This royal foundation laid the groundwork for the later University of Alcalá, which became a leading European institution. The initiative reflected a broader medieval trend toward institutionalized learning and scholarship.
1293
Sancho IV of Castile
Estudio de Escuelas de Generales
Alcalá de Henares
1426day.year
King Mohnyin Thado formally ascends to the throne of Ava.
Mohnyin Thado is crowned king of the Ava Kingdom, initiating a period of consolidation in Upper Burma.
On May 20, 1426, Mohnyin Thado was formally enthroned as king of Ava after defeating rival factions. His rise followed a series of campaigns that reunited the fragmented Burmese states. Thado’s reign focused on centralizing authority, improving administrative structures, and reviving Buddhist scholarship. He promoted trade along inland routes and supported the arts. His leadership set the stage for Ava’s emergence as a regional power in the 15th century.
1426
Mohnyin Thado
throne of Ava
1449day.year
The Battle of Alfarrobeira is fought, establishing the House of Braganza as a principal royal family of Portugal.
Supporters of King Afonso V defeat Infante Peter at Alfarrobeira, elevating the House of Braganza in Portugal.
The 1449 Battle of Alfarrobeira saw forces loyal to King Afonso V clash with those of his uncle, Infante Peter of Coimbra. The royal army achieved a decisive victory near Porto, and Peter was killed in the aftermath. The triumph solidified the House of Braganza’s status as Portugal’s foremost noble family. This outcome reshaped court dynamics and influenced royal succession for generations. The battle marked a turning point in 15th-century Portuguese politics.
1449
Battle of Alfarrobeira
House of Braganza
1497day.year
John Cabot sets sail from Bristol, England, on his ship Matthew looking for a route to the west (other documents give a May 2 date).
Explorer John Cabot departs Bristol aboard the Matthew, embarking on a westward quest for Asia.
In 1497, John Cabot sailed from Bristol under the patronage of King Henry VII with a small crew aboard the Matthew. His mission was to find a direct sea route to Asia by heading west across the Atlantic. Cabot’s voyage led to the first known European landfall on the North American mainland since the Norse expeditions. Though the exact landing site remains debated, his journey opened the door to later English exploration and colonization. Cabot’s expedition laid the groundwork for England’s future claims in the New World.
1497
John Cabot
Bristol
Matthew
May 2
1498day.year
Portuguese explorer Vasco da Gama discovers the sea route to India when he arrives at Kozhikode (previously known as Calicut), India.
Vasco da Gama reaches Kozhikode, India, confirming the sea route from Europe around Africa.
On May 20, 1498, Vasco da Gama arrived at the port of Kozhikode on India’s Malabar Coast, completing the first sea voyage from Europe to India. This achievement confirmed the maritime route around the Cape of Good Hope pioneered a year earlier. Da Gama’s expedition established direct trade links for spices, textiles, and other valuable commodities. The voyage marked a milestone in the Age of Discovery and shifted global economic power toward seafaring nations. It also heralded the beginning of Portuguese colonial and commercial expansion in Asia.
1498
Vasco da Gama
discovers the sea route to India
Kozhikode
1520day.year
Hernan Cortés defeats Pánfilo de Narváez, sent by Spain to punish him for insubordination.
Hernán Cortés defeats Pánfilo de Narváez in 1520, eliminating the rival expedition sent to arrest him and securing his command.
In May 1520, Hernán Cortés faced an unexpected challenge when Spain sent Pánfilo de Narváez to quell his growing power.
Despite Narváez's numerical advantage, Cortés outmaneuvered him through decisive tactics and alliances with indigenous groups.
The defeat of Narváez's force removed a direct threat to Cortés's authority in Mexico.
Captured soldiers were recruited into Cortés's army, bolstering his ranks.
This triumph paved the way for his eventual conquest of the Aztec Empire.
1520
Hernan Cortés
defeats
Pánfilo de Narváez
1521day.year
Ignatius of Loyola is seriously wounded in the Battle of Pampeluna.
During the siege of Pamplona in 1521, Ignatius of Loyola was gravely injured, an event that led to his spiritual transformation and the founding of the Jesuit order.
In May 1521, as Spanish forces besieged Pamplona, a cannonball struck Spanish soldier Íñigo López de Loyola, later known as Ignatius of Loyola.
He suffered severe leg fractures and endured a prolonged, painful recovery.
During this convalescence, he immersed himself in religious texts, sparking a profound spiritual awakening.
This period of reflection led him to form a vision for a new Catholic order focused on education and missionary work.
He eventually founded the Society of Jesus (the Jesuits), which played a pivotal role in the Counter-Reformation.
The injury at Pamplona thus became the catalyst for one of the most influential religious movements in Europe.
1521
Ignatius of Loyola
Battle of Pampeluna