Final answer:
In the 15th century, chain mail was replaced by plate armor due to advancements in military technology, including the use of crossbows, longbows, and firearms, which necessitated more protective gear.
Step-by-step explanation:
In the 15th century, chain mail was largely replaced by plate armor in Europe, which was a result of the continuous advancements in warfare and military technology. By the time of the Hundred Years' War, the efficacy of chain mail was diminished by the use of the longbow, crossbows, and eventually early firearms such as the arquebus. Plate armor offered superior protection against these weapons and became a key component in the equipment of a knight and other soldiers.
By the 14th century, the first cannons had been introduced, and the capture of Constantinople in 1453 highlighted the significance of artillery in warfare, further reinforcing the need for improved protective gear. Innovations in warfare strategy and technology, including the use of crossbows and firearms, necessitated more sophisticated armor, thus spurring the evolution from chain mail to full plate armor. This was a reflection of the ongoing arms race between weapon development and armor.