March – Welsh forces under Prince Dafydd ap Gruffydd, brother of Llywelyn ap Gruffudd, attack and take control of Hawarden Castle. The garrison is massacred and Constable Roger de Clifford is taken prisoner. Llywelyn who has sworn fealty to King Edward I (Longshanks), joins Dafydd in his revolt against the English. Their actions lead to the final English conquest of Wales, by Edward.
March 30 – War of the Sicilian Vespers: A group of Sicilian conspirators begins an uprising against the rule of King Charles I; over the next six weeks, thousands of French are killed. The rebellion forces Charles to abandon the planned crusade against the Byzantines, while still en route to the target city of Constantinople and allows King Peter III (the Great) to take over rule of the island from Charles (which in turn leads to Peter's excommunication by Pope Martin IV).
May 1 – Battle of Forlì: A French expeditionary army under Jean d'Eppe launches an assault on Forlì and breaches the outer wall. While they plunder the suburbs, Guido I da Montefeltro sends a small force out the gate on the opposite side of the city. In an ambush, Guelph and Ghibelline forces defeat the main army of d'Eppe, who is forced to retreat to Faenza. He requests Martin IV for more reinforcements, but this is refused.[1]
Summer – An Aragonese expeditionary army under Peter III lands in North Africa in Collo, in proclaimed support of a rebellion of the governor of Constantine, Ibn Wazir. The revolt is suppressed by Abu Ishaq Ibrahim I, ruler of the Hafsid Sultanate. Peter, wary of the situation in Sicily, sails off and fails to take advantage of the state of rebellion in North Africa. Ibrahim stabilizes his power and styles himself emir of the sultanate.[2]
June – The 24-year-old Prince Sancho, heir to the throne of Castile, assembles a coalition of nobles and starts a massive rebellion against his father, King Alfonso X (the Wise). He dispatches his brothers into the realm to claim strategically important cities and castles. Only the cities of Seville, Murcia, and Badajoz remain loyal to Alfonso, who becomes isolated politically and abandoned by most of his family.[3]
June 26 – King Denis I (the Poet King) marries the 11-year-old Elizabeth of Aragon, daughter of Peter III (the Great), in Trancoso. Elizabeth received the towns of Óbidos, Abrantes, and Porto de Mós as part of her dowry. Denis, known for his poetry, writes several poems and books himself, with topics of administration and hunting. During his reign, Lisbon becomes one of Europe's centers of art and culture.
July – Alfonso X (the Wise) allies himself with Abu Yusuf Yaqub ibn Abd al-Haqq, ruler of the Marinid Sultanate, who crosses the straits, and establishes a camp at Zahara de la Sierra, in southern Spain. Alfonso offers the Castilian royal crown of his father and grandfathers as a pledge of re-payment of a loan. Out of pity, Abu Yusuf gives him 100,000 gold dinars.[5]
August – Castilian forces under Sancho lay siege to Badajoz, who eventually retreat as the combined armies of Alfonso X (the Wise) relieve the city. Shortly after, Alfonso marches to Córdoba and demands the key of the city. This is refused by Diego López V de Haro, speaking on behalf of the magnates. Meanwhile, the Marinids plunder the Guadalquivir valley.
August 30 – Peter III (the Great) traveling with his fleet on a military expedition against Tunis, ends up in the Sicilian town of Trapani, after he was asked by the inhabitants of Palermo to help in the fight against Charles I.[6]
September or October – Battle of Lake Hód: Hungarian forces led by King Ladislaus IV successfully repel and defeat an invading Cuman army. Ladislaus receives the title "the Cuman" for his heroic victory.[8]
November – Castilian forces under Alfonso X (the Wise) reconquer Córdoba. Pope Martin IV issues a papal bull, forcing Sancho and his nobles to proclaim their allegiance to Alfonso ending the rebellion.
Dutch forces led by Floris V, count of Holland, attack and defeat the West Frisians at the battle of Vronen. He succeeds in retrieving the body of his father, William II, some 26 years dead.
King Stefan Dragutin breaks his leg while hunting and becomes ill. He abdicates the throne in favor of his younger brother, Stefan Milutin, who becomes ruler of Serbia (until 1321).
The form for the Trial of the Pyx, during which it is confirmed that newly minted coins conform to required standards, is established.
The first evidence is discovered of the existence of consolidated public debt in Bruges, confirming the expansion of use of annuities, to fund government expenditure to the Low Countries.[13]
^Kleinherz, Christopher (2004). Medieval Italy: An Encyclopedia, p. 473. Routledge.
^Meynier, Gilbert (2010). L'Algérie cœur du Maghreb classique. De l'ouverture islamo-arabe au repli (658-1518). Paris: La Découverte. p. 163. ISBN978-2-7071-5231-2.
^Joseph F. O'Callaghan (2011). The Gibraltar Crusade: Castile and the Battle for the Strait, p. 82. ISBN978-0-8122-2302-6.
^Morris, Marc (2008). A Great and Terrible King: Edward I and the Forging of Britain, p. 180. London: Hutchinson. ISBN978-0-09-179684-6.
^Joseph F. O'Callaghan (2011). The Gibraltar Crusade: Castile and the Battle for the Strait, p. 83. ISBN978-0-8122-2302-6.
^Chaytor, H.J. (1933). A History of Aragon and Catalonia, p. 103. London: Methuen. ISBN978-0-404-01479-7.
^ Harris, Jonathan (2003). Byzantium and the Crusades, p. 180. London: Hambledon. ISBN978-1-85285-298-6.
^Berend, Nora (2001). At the Gate of Christendom: Jews, Muslims and "Pagans" in Medieval Hungary, c. 1000–c.1300. Cambridge University Press. p. 147. ISBN978-0-521-02720-5.
^Prestwich, Michael (1997). Edward I, pp. 191–92 (updated ed.). New Haven: Yale University Press. ISBN0-300-07209-0.
^Hywel Williams (2005). Cassell's Chronology of World History, p. 149. ISBN0-304-35730-8.
^Zuijderduijn, Jaco (2009). Medieval Capital Markets. Markets for renten, state formation and private investment in Holland (1300-1550). Leiden/Boston: Brill. ISBN978-90-04-17565-5.
