The 1210s was a decade of the Julian Calendar which began on January 1, 1210, and ended on December 31, 1219.
- May – The Second Parliament of Ravennika is held at Ravennika in Central Greece, resulting in a concordat between the princes of Frankish Greece and the Roman Catholic clergy.
- July 18 – Battle of Gestilren: Former king Sverker II of Sweden is defeated and killed, by the reigning king Erik X.
- November 18 – Otto IV, Holy Roman Emperor is excommunicated by Pope Innocent III, for invading southern Italy in defiance of the Concordat of Worms.
- November 21 – King Eric X of Sweden is crowned, which is the first known coronation of a Swedish king. Shortly thereafter, he marries the Danish princess Richeza, in order to strengthen his relationship to the Danish king Valdemar the Conqueror. Valdemar used to support King Sverker II, but through the marriage, Valdemar makes peace with his former enemy, Eric.
- King John I of England raises £100,000 from church property as an extraordinary fiscal levy; the operation is described as an “inestimable and incomparable exaction” by contemporary sources.
- Livonian Crusade – Battle of Ümera: Estonian forces defeat the Livonian Brothers of the Sword.
- The citadel of the Acrocorinth in Greece surrenders to the Crusaders, after a five-year siege.
Arts and culture
- July 10 – The most severe of several early fires of London burns most of the city to the ground; over 3,000 people die, many of them by drowning in the Thames. According to a contemporary account, "An awful fire broke out on the Southwark side of Lond. Bridge; and by some means, while it was raging, a fire broke out at the other end also, and so hemmed in the numerous crowds who had assembled to help the distressed. The sufferers, to avoid the flames, threw themselves over the bridge into boats and barges; but many of these sunk, the people crowding into them.".
- July 16 – Battle of Navas de Tolosa: The Christian kingdoms of Spain decisively defeat the Almohads, and the victory leaves the Kingdom of Castile in a difficult financial position, as numerous soldiers have to be paid by the treasury.
- December – Frederick II of Hohenstaufen is crowned King of Germany, with the support of Pope Innocent III.
- The Children's Crusade for the Holy Land is organised. There are probably two separate movements of young people, both led by shepherd boys, neither of which embark from Europe, but both of which suffer considerable hardship:
- The contemplative Order of Poor Clares is founded by Clare of Assisi.
- In Japan, Kamo no Chōmei writes the Hōjōki, one of the great works of classical Japanese prose.
- Bran Castle is erected by the Teutonic Knights, in the Southern Carpathians (present day Romania).
- John of England impounds the revenue of all prelates appointed by bishops who had deserted him at his excommunication. He remains on good terms, however, with churchmen who stood by him, including Abbot Sampson, who this year bequeaths John his jewels.
- The Banner of Las Navas de Tolosa is begun. It is a trophy of Ferdinand III of Castile, and will end up in the
Museo de Telas Medievales.
- February 15 – John, King of England, lands an invasion force at La Rochelle in France.
- July 27 – Battle of Bouvines: Philip II of France defeats an army of Imperial German, English and Flemish soldiers led by Otto IV, Holy Roman Emperor, in the Kingdom of France, ending the Anglo-French War (1213–14).
- Summer – King Alfonso VIII of Castile besieges Almohad troops in Baeza. The famine experienced in the peninsula is such that neither army is able to fight.
- September 18 – The Treaty of Chinon is signed by John, King of England, and Philip II of France, recognising the Capetian gains from the Angevin Empire.
- October 5 – Upon the death of their father, King Alfonso VIII of Castile, and of their mother, Eleanor (October 31), Berenguela becomes the regent of her young brother, King Henry I.
- December 4 – William the Lion, King of the Scots, dies, having reigned since 1165; he is succeeded by his son, Alexander II (crowned at Scone on December 6), who will reign until his death in 1249.
- The German city of Bielefeld is founded.
- March 4 – King John of England makes an oath to Pope Innocent III as a crusader, to gain his support.
- May 31 – Mongol conquest of the Jin dynasty: after the long Battle of Zhongdu, Genghis Khan's Mongols capture and torch Beijing (the city burns for more than a month).
- June 15 – King John of England is forced, by rebellious barons of England at Runnymede, to put the Great Seal of the Realm on a set of articles confirming their rights and those of the towns and Church, and confirming the status of trial by jury, which on June 19 is confirmed as the Magna Carta.
- August – King John of England rejects the Magna Carta, leading to the First Barons' War.
- August 24 – Pope Innocent III declares the Magna Carta invalid.
- November 11 – The Fourth Council of the Lateran gathers in Rome under Pope Innocent III, who adopts the title "Vicar of Christ".
- December – First Barons' War: Alexander II of Scotland invades northern England.
- Otto IV, Holy Roman Emperor, is excommunicated and forced to abdicate as Emperor and King of Burgundy, replaced by Frederick II (King of the Romans 1212–1250).
- The Dominican Order is founded, according to some sources.
- Bhiksu Ananda of Kapitanagar completes writing the holy Buddhist book Arya Astasahasrika Prajnaparamita (sutra), in gold ink in Ranjana script.
- 1215–1216 – The Macy Jug, from Iran, is made. It is now kept at The Metropolitan Museum of Art, New York.
- Kalinga Magha, from Kalinga Province in India, lands in Sri Lanka with a force of 24,000 men, to capture the city of Polonnaruwa and depose its king, Parakrama Pandya.
- January – First Barons' War: The English army sacks Berwick-on-Tweed, and raids southern Scotland.
- April 10 – Upon the death of Erik Knutsson, he is succeeded by his rival Johan Sverkersson, as king of Sweden.
- April 22 – Battle of Lipitsa: Mstislav the Daring and Konstantin of Rostov defeat their rivals for the rule of the Principality of Vladimir-Suzdal.
- May 21 – First Barons' War: Prince Louis of France, the future King Louis VIII, invades England in support of the barons, landing in Thanet. Entering London without opposition, he is proclaimed, but not crowned, King of England at Old St Paul's Cathedral.
- July 24 – The French Albigensian Crusaders of the castle of Beaucaire surrenders to Raymond, future count of Toulouse.
- October 18 or 19 – John, King of England, dies at Newark Castle, Nottinghamshire; he is succeeded by his nine-year-old son Henry, with William Marshal, Earl of Pembroke, as regent. The young Henry III of England is crowned at Gloucester on October 28.
- November 12 – William Marshal and the papal legate to England, Guala Bicchieri, issue a Charter of Liberties, based on the Magna Carta, in the new King of England's name.
- Dresden receives city rights.
- In England, Roger of Wendover begins to cover contemporary events, in his continuation of the chronicle Flores Historiarum.
- Mukhali returns to Genghis Khan's camp in Mongolia, and receives the hereditary title of prince, a golden seal, and a white standard with nine tails and a black crescent in the middle. He is appointed commander in chief of operations in North China.
- The Fifth Crusade reaches the Holy Land.
- April 9 – Peter II of Courtenay is crowned emperor of the Latin Empire of Constantinople at Rome, by Pope Honorius III.
- May 20 – First Barons' War in England: Occupying French forces are defeated at the Battle of Lincoln, by English royal troops led by William Marshal, Earl of Pembroke, and survivors are forced to flee south.
- June 6 – King Henry I of Castile dies aged 13, from the fall of a roof tile in Palencia, an event which his regent, Álvaro Núñez de Lara, attempts to conceal. Henry's sister Berengaria succeeds to the throne.
- June – Haakon Haakonsson becomes King Haakon IV of Norway, following the death of Inge II, and largely ends the civil war era in Norway, reigning until 1263.
- August 24 – First Barons' War: In the Battle of Sandwich in the English Channel, English forces destroy the French, and the French mercenary Eustace the Monk is captured and beheaded.
- August 31 – Ferdinand becomes King of Castile, upon the abdication of his mother Berengaria.
- September 12 – The First Barons' War in England is ended by the Treaty of Kingston upon Thames; The French and Scots are to leave England, and an amnesty is granted to rebels.
- September 20 – The Treaty of Lambeth is signed, ratifying the Treaty of Kingston.
- September 21 – Livonian Crusade: The Livonian Brothers of the Sword and allied Livs and Letts defeat the Estonian army in the Battle of St. Matthew's Day, and kill their leader Lembitu.
- October 18 – Fifth Crusade, Reconquista: Alcácer do Sal is reconquered by the troops of King Afonso II of Portugal.
- November – In the Kingdom of Castile, former regent Álvaro Núñez de Lara is captured, and forced to relinquish all his castles.
- Stefan Nemanjić is elevated to be the first King of the Serbian lands by Pope Honorius III, and crowned by Stefan's brother, Archimandrite Sava, in Žiča.
- A decree made in England establishes that only Englishmen can be clergy of Ireland.
- The northern French city of Rheims emits the first recorded public life annuity in medieval Europe. Theretofore, this type of instrument had been mostly issued by religious institutions. The emission by Rheims is the first evidence of a consolidation of public debt that is to become common in the Langue d'Oïl, the Low Countries and Germany.