The Middle Ages are often seen as a time when the people of the Europe saw their use of technology stall as not many advances were made in terms of warfare and general life.
However, the European took a piece of ancient Chinese technology and developed it long before gunpowder was brought to Europe and created one of the most destructive weapons ever produced in the Trabuco; this piece of European siege weaponry was initially developed by Chinese generals but came into common use in the Middle Ages across Europe when boulders of up to 200 pounds were thrown at the walls of cities under siege on merriam-webster.com.
As a weapon, the Trabuco uses the basic principles of science including the lever providing more force to throw an object when the opposite end of the Trabuco arm contains a weight which is pulled tight before being released to create the power to throw an object hundreds of yards. At the other end of the arm is a piece of material stretched to hold a rock or boulder which is thrown into the air towards a walled city during a siege. The central portion of the Trabuco is the fulcrum across which the arm is pulled tight and released to provide movement and thrust.
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Upon its first invention in China around 300 B.C., the first Trabuco required a large number of men to propel the arm and generate the power needed to throw a large stone across the battlefield. The initial Chinese design according to wikipedia.org was updated and improved upon by European generals and engineers who introduced the counterweight to the Trabuco which would make it more consistently effective as a weapon to be used when a siege was in place; a range of missiles were used with the Trabuco to cause the maximum amount of damage and panic across a besieged city including stones, sharp wooden stakes, and firebrands. By the time the Trabuco reached its peak period of use in the 13th-century around 2,000 weapons could be launched from the Trabuco each day.
Find more about Trabuco: http://www.spanishdict.com/translate/Trabuco