The Crossbow: Han Bronze Triggers, Steel Cranequins and Silent Commandos

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The crossbow solved a human problem: a heavy war bow forces the archer to hold enormous tension while aiming, but a mechanical latch holds it for him. The trade-off is physics. A crossbow's short stroke means even a huge draw weight transfers energy inefficiently, and loading is slow, yet a farmer could become a lethal marksman in an afternoon. Ancient China saw this first. Cast bronze crossbow locks date to around 650 BC, examples lie buried with the Terracotta Army, and under the Qin and Han dynasties three-piece bronze triggers were cast to such uniform tolerances that parts were interchangeable. Han inventories favored crossbows over bows, and massed volleys were credited with victories over northern nomadic cavalry.

A parallel line ran through the Mediterranean, from the Greek gastraphetes, or belly bow, of the 5th century BC to the Roman crossbowmen Vegetius mentioned without bothering to describe. Medieval Europe moved from wooden prods to composite bows in the 13th century and solid steel in the 14th, which demanded windlasses and geared cranequins to span. Gunpowder pushed the weapon off the open battlefield after Cerignola in 1503, but it survived in niches: World War I grenade launchers, booby-trap clearance, counterterrorism and marine biology.

• The spine of the Han trigger's J-shaped nut stuck up above the stock and served as an elevation sight lined up with the bolt tip.
• Entry-level Han soldiers had to span a 168-pound crossbow, and elite troops used their legs and backs to draw bows of up to 750 pounds.
• A medieval crossbowman managed about two shots a minute, working behind a full-body pavise shield held by a partner.
• The French and British Sauterelle, or grasshopper, of World War I weighed over 50 pounds and lobbed grenades into enemy trenches.
• Researchers fire blunt-stopped bolts at whales and dolphins that bounce off and collect a small plug of blubber for biopsy.