How did Spanish arquebusiers affect the Battle of Pavia?

At the Battle of Pavia in 1525, Spanish arquebusiers played a decisive role in the defeat of Francis I. As the French forces struggled with confusion and poor visibility due to fog, these soldiers—armed with early firearms featuring triggers—inflicted heavy casualties on the French ranks.1

The effectiveness of the arquebusiers was particularly notable in their ability to neutralize key French leadership and personnel; for instance, the veteran Duke of Tremoille was killed by a shot through the heart. Their presence marked a significant shift in military history, as the battle demonstrated the growing dominance of gunpowder over traditional medieval tactics, such as the heavy cavalry charge led by Francis I, which proved ineffective against the new weaponry. By the early 16th century, the integration of such firearms into infantry formations, such as the Spanish tercio, had begun to fundamentally alter the nature of European warfare.12