Crossbows were initially drawn by hand, by placing ones foot in the triangular stirrup
-like thing in front of the bow, grabbing the string
with straight arms and straightening the leg (Another option was to attach the string to a hook on the belt), but after the introduction of the steel
bow (which replaced the bows made from wood
, often by laminating different materials) around 1400
, the increased draw-weight
made this impossible, and a lever
had to be used.
In 1139, pope Innocentius II declared the use of a crossbow against fellow (or not-so-fellow, one might presume) christians a crime, but since almost everyone (except perhaps the Welsh) had realised the advantage of the crossbow over the longbow - the flatter trajectory made aiming easier, no one paid much attention to the pope in this matter.
The ammunition used by crossbows is called bolts or quarrels.