Broken Promise to Mary Tudor: In 1503, King James IV of Scotland had signed the Treaty of Perpetual Peace with England during the reign of King Henry VII, agreeing to marry Henry's eldest daughter, Margaret Tudor. After Henry VII's death and succeeded by Henry VIII, James IV failed to honor this arrangement and instead married Margaret, daughter of John de la Pole, Earl of Lincoln. Henry VIII regarded this move as a form of betrayal.
Support for Pretender to English Throne: King James IV continued to provide support to Perkin Warbeck, a pretender to the English throne during the reign of Henry VII. Henry feared that King James' support for potential adversaries posed a threat to his authority.
England's Invasion of France: In June 1513, King Henry VIII invaded France as part of a European conflict known as the War of the League of Cambrai. King James saw this campaign as an opportunity to attack England, as many of its military forces were engaged abroad.
Desire to Reclaim English-Occupied Lands: Scotland aimed to restore the territories of Berwick and Norham, which had been occupied by England. King James IV sought to assert his authority and regain land that he believed rightfully belonged to Scotland.
These factors combined to spark tensions between Scotland and England, eventually leading to the outbreak of war and culminating in the Battle of Flodden in 1513.