First developed in antiquity, "modern" plate armor (with well fitted and moving parts) was first used by the Iranians (Parthians) about a thousand years before it came into general use in Europe from the 13th century onward. Plate had become the standard form of armor by the late 15th century, replacing chain mail. Plate was just that, a sheet of metal (about as thick as that used to make cars in the 1950s) and formed into a breat plate (front and back) a flexible metal "skirt" as well as articulated coverings for the arms and legs. Atop it all was a helmet and face place, as well as metal shoes and gauntlets. These all fitted together in such a way as to overlap, leaving few vulnerable points. The heaviest suit known weighed about 90 pounds, belonging to Duke Ferry of Lorraine, who was killed at Agincourt in 1415, but most weighed about 70 pounds. Plate armor was made to order, thus it was very expensive, costing from 10,000 to 50,000 ducats depending on how complete and fancy the suit was. Sort of like the various classes of luxury automobiles nowadays. Because each suit was made to the measurements of the user, the weight was evenly distributed and was not as cumbersome as one would think. As 20th century experiments revealed, college atheletes (selected to fit in 15th century suits of armor) could lie down and jump to a standing position, do jumping jacks, and mount a horse with no trouble. A modern infantryman often totes as much or more equipment into action as did a medieval knight, and most of the grunt's gear is carried on his back, nor does he have a horse to help him.