Why did medieval powers often arm their soldiers with padded jacks or padded gambeson (cloth armor) if such armors could easily be pierced by spears, which were the primary weapon at the time?

by [deleted]
wotan_weevil

If such armors could easily be pierced by spears (and therefore also arrows), which were the most important and common weapons on the battlefield, there would have been little point in wearing such armour. That such armour was common on battlefields in various parts of the world at various times strongly suggests that it was effective. The effectiveness of textile armours was praised in contemporary sources, such as descriptions of Mesoamerican textile armours by Spanish writers (who sometimes preferred such armour over Spanish mail and plate), and descriptions of African quilted armours from the Sahel (described as effective against arrows and spears, and less so against muskets), further suggests that they were effective.

Good quality modern tests of effectiveness appear to be lacking. Modern tests typically use either loose layers of cloth, sometimes completely loose, sometimes folded, and sometimes sewn at the edges. Sometimes, the test cloth is loosely quilted. Surviving examples of multi-layer textile armour are usually closely quilted (and therefore quite stiff), quite different from the layered cloth used in most modern experiments. Some examples of quilted armours:

These examples are African, from the eastern and western Sahel (e.g., Sudan and Nigeria). Since tight quilting like this adds considerably to the labour cost of the armour, and makes it stiffer (and therefore possibly less comfortable to wear), it presumably offers significant protective benefit. This suggests that the loosely-layered textile armours usually tested are less protective. Despite this, they appear to offer good protection against spears. For example, in these tests,

the armour provided significant (but not complete) protection against arrows, and stopped spear thrusts (and sword and axe cuts). In the tests reported in

  • Aldrete, G. S. & Bartell, S. & Aldrete, A., Reconstructing Ancient Linen Body Armor: Unraveling the Linothorax Mystery, Johns Hopkins University Press, 2013.

the quilted linen test armours similarly provided significant (but not complete) protection against arrows with energies of up to 70J. The quilted armours tested were relatively thin, 15 layers compared to the 30 layers historically described as required for good protection against arrows. Extrapolating these results to 30 layers, arrows from high draw weight war bows should be stopped. The test results in

  • Williams, Alan, The knight and the blast furnace, Brill, 2002

were similar. Notably, doubling the thickness of the layered linen improved the protection by 2.5 times.