Longbow. When people think of major military inventions, they usually think of the gun, which did enable the European conquest and colonization of Africa and the Americas. But if you want to talk about a weapon that triggered the greatest historic change in the least amount of time, the longbow gets my vote. The longbow changed history on three specific days in 1346, 1356, and 1415. On those days, English and French armies clashed at Crécy, Poitiers, and Agincourt. Why was the longbow so important? Because it enabled leather-clad English commoners to defeat ironclad French knights.

Throughout medieval times, a European army consisted fundamentally of armored noblemen on armored horses. These living tanks personally won or lost battles, and that's what made nobles noble. At Crécy, Poitiers, and Agincourt, the French army had roughly three times as many knights as the English, but the English army had archers armed with a new kind of bow. It differed from the old kind of bow only in length. But that extra length gave it just enough power to shoot some hundred feet further and pierce armor. Just like that, the armored knight was finished as a significant element in war. From this time forward, power began shifting from the armored class to the moneyed class--which soon came to include merchants, manufacturers, and bankers.

The Halberd

Also referred to as the halbard and the halbert. Used across Europe from the 13th century forward, the halberd is probably the most famous and recognizable weapon of the polearm group. The halberd was used most extensively in the 15th and 16th centuries and was the most versatile polearm ever developed. It incorporated an axe blade, a spear point, and a pick/hammer beak. It could be used to hook an enemy to the ground, even off horseback. It could be thrust or used for chopping as well. Combat training in the use of halberds was fairly extensive as they could be used lethally or non-lethally (to trip, knock down, or otherwise subdue an opponent). While halberds were uncommon as combat weapons after the 17th century, they were carried as symbols of authority and rank well into the 19th century. The Swiss developed the halberd and were the most famous employers of halberdsmen in their ranks. Even today, the Swiss guards at the Vatican carry halberds (for appearances only; they keep automatic weapons in the armory); the Tower of London Beefeaters are also famous wielders of halberds today.