shell. Hawley, however, questions the historical accuracy of this drawing since it departs in important ways from the 16th-century ships, such as its lack of the reported iron spikes (see image) and the different shape and number of the dragons' heads displayed at the bow. The Korean designation "turtle ship" is already attested in the year 1413, for an early type of the vessel which by all accounts did not feature any armor. Hawley puts forth the hypothesis that the idea of ironclad turtle ships has its origins in the writings of late 19th-century Westerners returning from Korea. The progression from simple comparison to a statement that the turtle ships anticipated the modern ironclad by centuries can be roughly charted in retrospect, starting no earlier than ca. 1880. Coming in touch with local tales of ancient armored ships in a period which saw the rise of Western-type ironclad warship to global prominence, these authors may have naturally conjured up the image of metal armor instead of a more traditional heavy timber shell. For instance, during the General Sherman Incident, the Koreans initially constructed an improvised turtle ship, which was protected by metal sheeting and cowhides to destroy General Sherman but failed to penetrate its iron hull at the cost of one of their sailors. When the French Navy threatened Korea, the government ordered an ironclad ship be built "like the turtle ship." However, despite all efforts the design failed to float. Turnbull believes that the 19th-century experience should not rule out a "limited amount of armor plating in 1592". Weapons Dragon's head The dragon's head was placed on the top of the ship at the bow. Several different versions of the dragon's head were used on the turtle ships. The dragon's head was first placed as an early form of psychological warfare in order to scare Japanese soldiers. One version carried a projector that could release a dense toxic smoke that was generated to obscure vision and interfere with the Japanese ability to maneuver and coordinate properly. Yi's own diary explains that a cannon could be fitted in the mouth of the dragon to be fired at enemy ships. This type of cannon was usually a hwangja-chongtong. Spikes Metal spikes were used to cover the top of the turtle ship to deter boarding tactics used by the Japanese. According to historical records, the spikes were covered with empty rice sacks