Which political events between 750-1500 led directly to a declaration of war?

The Hundred Years' War was triggered by political events such as the dispute over the French throne between Edward III and Philip VI.

The Hundred Years' War, a series of conflicts waged from 1337 to 1453, was primarily sparked by political events and disputes over the French throne. Edward III of England claimed the French crown as his own, challenging the reign of Philip VI. This claim was based on his mother, Isabella, being the sister of the previous French king, Charles IV. However, the French rejected this claim, citing Salic law, which prohibited succession through the female line. This disagreement over the rightful heir to the French throne was a significant political event that led directly to the declaration of war.

Another political event that led to war during this period was the War of the Roses in England. This was a civil war for control of the throne of England, fought between supporters of two rival branches of the royal House of Plantagenet: the House of Lancaster, associated with a red rose, and the House of York, whose symbol was a white rose. The political tension and power struggle between these two houses led to a series of violent wars from 1455 to 1487.

In the Iberian Peninsula, the Reconquista, the centuries-long struggle to reclaim Spain from the Moors, was another significant political event that led to war. The Christian kingdoms of Castile, Aragon, and Portugal waged war against the Muslim emirates in the south. The fall of the emirate of Granada in 1492 marked the end of the Reconquista and the beginning of the Spanish Inquisition.

In the Middle East, the Crusades were a series of religious wars initiated, supported, and sometimes directed by the Latin Church in the medieval period. The best-known Crusades are the campaigns in the Eastern Mediterranean aimed at recovering the Holy Land from Muslim rule. The political and religious tensions between the Christian and Muslim worlds were significant factors that led to these wars.

These political events between 750 and 1500, driven by disputes over thrones, religious differences, and power struggles, led directly to declarations of war and shaped the course of history.