Edmund Ironside vs John I of Castile

Edmund Ironside defeated Cnut the Great at Penselwood in Somerset. This victory was part of a series of battles as Edmund fought to defend his claim to the English throne after his father Ethelred's death.

Edmund fought Cnut to a draw at Sherston in Wiltshire. The battle was indecisive, with both sides suffering heavy casualties, and neither gaining a strategic advantage.

Cnut decisively defeated Edmund at Assandun (possibly Ashingdon in Essex). The defeat forced Edmund to negotiate a partition of England with Cnut.

Edmund and Cnut agreed to divide England: Edmund ruled Wessex, Cnut ruled the rest. The treaty also stipulated that if one died, the other would inherit the entire kingdom.

Edmund died on November 30, 1016, shortly after the Treaty of Olney. His death allowed Cnut to become sole king of England, ending Anglo-Saxon resistance.

Upon the death of King Ferdinand I of Portugal without a male heir, John I of Castile asserted his claim to the Portuguese throne through his wife Beatrice, daughter of Ferdinand I. This claim was contested by Portuguese nobles, leading to the 1383-1385 Portuguese interregnum.

John I of Castile led his army against Portuguese forces commanded by John of Aviz at Aljubarrota. The Castilian army was decisively defeated, securing Portuguese independence and ending Castilian claims to the Portuguese throne. The battle established the Aviz dynasty in Portugal.

Following the defeat at Aljubarrota, John I of Castile signed the Treaty of Windsor with England, formalizing an alliance between Castile and England. The treaty included provisions for mutual military support and trade agreements, strengthening Castile's position in the Hundred Years' War.