Armour started to change again in the latter part of the 16th century, when many of the plate features of the standard army armour were replaced. This was done to reduce the amount of weight that the foot soldiers had to carry so they could move around easier and faster.
However, back and breastplates were still in use during the 18th century and throughout the Napoleonic era, with a number of different armies around the world requiring the use of armour in some form or another. Once weapons such as muskets came into being, armour was almost redundant as most metal plating could be pierced, but it did still offer a small amount of protection and continued to be used in conflicts such as the American Civil War.
During World War I, armour was used by the French cavalry. They had plate armour, which was painted dark. Canvas wrap was used to cover the helmets that they wore. They knew that this would only offer protection against sabres and similar weapons. During WWI, the other types of weapons in use included rifles and machine guns, so any armour in use would offer very little protection.