Kettle Hats, also often known as „Chapel de fer” or Eisenhut with their broad rim were very effective to turn attacks from above be it a sword blow from a rider or a missile thrown from a wall.
These properties lead to the point that it was a helmet almost exclusively used by infantry.
The type as such came most probably with the end of the first crusade (beginning of the 12th century) from Byzantium to Europe where it rapidly spread.
It was in use for many centuries and only vanished for a short period during the 18th and 19th century.
During the end of the 19th century and especially during World War I the advantages of the design were rediscoverd.