Lanyards were, and are, made from a heavy twine. The sash cord, which would have been linen, and about 3/8 inch in diameter was used for binding material for field battlements, especially for making fascines. Light artillery artificers carried 6 two pound coils of the cord, and the carriage maker's chests that accompanied the mountain howitzer carried two such coils.
You won't find this information in the Ordnance manuals, but in the field fortification manuals. Only took me 11 years to figure out.