Video: Up-close look at the incredible power of a 'super rocket' that fired 100 arrows at once in the 15th century.

What is Hwacha? This article will reveal what made the Hwacha machine so terrifying to the Japanese army.

The Hwacha (literally "fire chariot") is a weapon developed in Korea and used by the military on the battlefield. It is best known for its deployment in the Imjin War, a conflict that took place in the last decade of the 16th century AD and is also known as the Japanese invasion of Korea. The Korean defenses' use of the Hwacha was one of the reasons for Japan's failure in its campaign to conquer the Korean peninsula.

The Hwacha is described as possibly one of the best early multi-barreled rocket launchers. Essentially, the weapon consisted of a two-wheeled cart with a board perforated with numerous holes. Each hole was filled with a singijeon (meaning 'magic machine arrow'). This was a type of arrow propelled by a gunpowder tube attached to its axle. In other words, the singijeon was an early type of rocket. The first hwachas were capable of firing up to 100 arrows per volley. The design was later improved to fire up to 200 arrows per volley.

The Hwacha is made of wood. The launcher consists of dozens of tubes arranged in rows. Inside each tube is a 1.1-meter-long arrow with a propellant-filled paper tube near the tip, connected by a slow-burning fuse. With just one ignition, all the arrows on the launcher will fire in 2-3 seconds. This launcher is mounted on two wheels for increased mobility.

The heavy arrows fired from the hwacha are powerful enough to penetrate all types of armor and shields at a distance of 100-150m. If fired from a high position and using lighter arrows, the hwacha's range can increase to 300-500m.

In the battle against Japanese pirates in 1419, the Hwacha rocket system helped the Korean navy completely annihilate the pirate forces. This is evidence of the formidable power of this weapon.

1. Video: Close-up view of a machine that crushes boulders and concrete in the blink of an eye.