However, with the arrival of gunpowder and cannons by the time of Henry VI, fortifications like castles became increasingly obsolete. 1485 marked the ascension of the Tudor Henry VII to the throne and the end of the Wars of the Roses that had left the royal coffers in deep trouble-Yorkists had raided the treasury just after the death of Edward IV. In 1487 Henry passed laws against livery and maintenance, which checked the nobility's ability to raise armies independent of the crown, and raised taxes on the nobility through a trusted advisor, John Morton.