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 casual comparison to a statement of fact 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 armoured 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 armour, instead of a more traditional heavy timber shell. For instance, when Korea was threatened by the French Navy, 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".