Final answer:
Castles had high openings in the walls to allow defenders to shoot arrows or projectiles, have a wider field of vision, and use defensive mechanisms such as boiling oil.
Step-by-step explanation:
Castles had high openings in the walls for several reasons. Firstly, these high openings, also known as arrow slits or loopholes, allowed defenders to shoot arrows or other projectiles at attackers while keeping themselves protected. The narrow openings made it difficult for enemies to enter the castle or shoot back effectively.
Secondly, the height of the openings provided a strategic advantage by allowing defenders to have a wider field of vision. They could see approaching enemies from a distance and prepare for an attack.
Lastly, the high openings in the walls allowed for the use of defensive mechanisms such as boiling oil or hot tar, which could be poured on attackers below.