The story was entertaining, and frightening, but was widely deemed too far-fetched to be believable

Recently completed and very much enjoyed Erik Larson's Dead Wake. Page 30. A great example that ideas circulate long before they become accepted. In this instance, an understanding of the true implications of submarine warfare. And it is not as if the ideas were circulating only within insular communities. A.C. Doyle was a widely read author and respected public intellectual.

At the beginning of the war, neither Germany nor Britain understood the true nature of the submarine or realized that it might produce what Churchill called “this strange form of warfare hitherto unknown to human experience.”

Only a few prescient souls seemed to grasp that the design of the submarine would force a transformation in naval strategy. One of these was Sir Arthur Conan Doyle, who, a year and a half before the war, wrote a short story (not published until July 1914) in which he envisioned a conflict between England and a fictional country, Norland, “one of the smallest Powers in Europe.” In the story, entitled “Danger!,” Norland at first seems hopelessly overmatched, but the little country has a secret weapon—a fleet of eight submarines, which it deploys off the coast of England to attack incoming merchant ships, both cargo and passenger. At the time Doyle conceived his plot, submarines did exist, but British and German naval commanders saw them as having little value. Norland’s submarines, however, bring England to the verge of starvation. At one point, without warning, the commander of the submarine fleet, Capt. John Sirius, uses a single torpedo to sink a White Star passenger liner, the Olympic. England eventually surrenders. Readers found that last attack particularly shocking because the Olympic was a real ship. Its twin had been the Titanic, lost well before Doyle wrote his story.

Intended to sound the alarm and raise England’s level of naval preparedness, the story was entertaining, and frightening, but was widely deemed too far-fetched to be believable, for Captain Sirius’s behavior would have breached a fundamental maritime code, the cruiser rules, or prize law, established in the nineteenth century to govern warfare against civilian shipping. Obeyed ever since by all seagoing powers, the rules held that a warship could stop a merchant vessel and search it but had to keep its crew safe and bring the ship to a nearby port, where a “prize court” would determine its fate. The rules forbade attacks against passenger vessels.

In the story, Doyle’s narrator dismisses as a delusion England’s belief that no nation would stoop to such levels. “Common sense,” Captain Sirius says, “should have told her that her enemy will play the game that suits them best—that they will not inquire what they may do, but they will do it first and talk about it afterwards.” Doyle’s forecast was dismissed as too fantastic to contemplate.