1461:

The Battle of Towton

The deadliest battle of the Wars of the Roses, Towton secured the throne of England for the recently-crowned King Edward IV. The Lancastrians, having failed to take London and prevent the coronation, retreated before the armies of Edward and Warwick. The Yorkists caught up with them on Palm Sunday. The battle raged for 10 hours in a snowstorm until John Mowbray, duke of Norfolk, arrived with fresh troops and the Lancastrians fled. The fugitives were hunted down and slaughtered.

1561:

Santorio Santorio

Santorio was the first pysician to employ instruments of precision to medical practice. His philosophy of using sensory experience before consulting the classical authorities and his experimental procedures contributed greatly to the development of medical science.