The final step in infantry armor is plate armor, a heavy and expensive armor that is nonetheless able to withstand all types of blows. Soldiers must have received chain mail, and before that scales, prior to getting their nice, shiny plates.
The people of Brittany do not have this technology available, perhaps due to a disregard for infantry. Neither, strangely enough, do the Flemish.
Researched at: Blacksmith
Cost: 300 Food, 150 Florins
Effect: Infantry +1/2 armor