Answer:
One reason was that many countries had formed their own standing armies. They paid soldiers to train and fight. They no longer needed lords to come fight as knights. The other reason was a change in warfare. Battle tactics and new weapons such as longbows and firearms made the heavy armor the knights wore cumbersome and useless. This made it much easier to arm a soldier and pay for a standing army.
Step-by-step explanation:
One reason was that many countries had formed their own standing armies. They paid soldiers to train and fight. They no longer needed lords to come fight as knights. The other reason was a change in warfare. Battle tactics and new weapons such as longbows and firearms made the heavy armor the knights wore cumbersome and useless. This made it much easier to arm a soldier and pay for a standing army.