serge moved into ME, from OFr, sarica, starting in latin as serica, silken garments, <sericus, silken, or literaly, of the Seres, an oriental people, and most likely from the original chinese word for silk se>
a stong twilled fabric with a noticiable diagonal rib, used for suits and coats..
silk is incredible strong, and was highly desired as an undergarment-- no, not that reason! usually, an arrow could not peirce it. so, while the arrow might go through the skin, it pulled the un peirced shirt with it..
this made it much easer to remove the arrow, (the shirt was twisted round the arrow shaft, and the cloth was pulled out.
this reduced internal damage, and once washed, the shirt was still good! it was more expensive than mail, and other metal armor, but it was very light weight, and cooler, and less restricting...
OP
