Reported in Scientific American, This Week in World War I: July 24, 1915

The British Royal Navy commanded the sea during World War I; had it not, Britain and France would not have been able to feed and arm themselves with imported food, raw materials and weapons. Germany and Austria were reluctant to send their fleets to challenge the Royal Navy, but kept up a very active campaign with sea mines and submarine attacks.

Submarines had their limitations but they took a large toll on Allied naval and merchant ships during the war. The main advantage of a sub was that while it was submerged it was virtually invisible and almost impervious to any weapon available in 1915. Only when it came to the surface was it vulnerable to gunfire or ramming. Those depth charges often seen in the movies were first proposed as “dropping mines” in 1913, but practical versions were not developed until 1915, and the first successes came in 1916. Ships at first carried just two of these crude barrel-like weapons, with sailors rolling them off the stern above where they thought submarines might be. Other devices were even less effective.

The anti-submarine weapon presented in the July 24 issue of Scientific American, pictured here, seems ridiculous to me. There was a vanishingly small chance of looping one of these gadgets over a sub in open water, and then having the trailing ropes foul the submarine’s propellors, as it was designed to do. The device was attached to a surface float that let off a smoky flare to alert naval vessels nearby that a submarine was present. Publishing this idea  is really evidence that existing technologies for sinking submarines were critically limited. Closer to shore, the submarine did face real risks: moored mines and anti-submarine nets stretched across harbors sank or caught a few submarines during the war.

In the U.S. thousands of private inventors stepped up to provide ideas for fighting subs. Thomas Edison was instrumental in creating a Naval Consulting Board to explore new technologies, and he himself spent 18 months working on naval technologies. As with inventions in any field, many were useless. In fact, on September 29, 1917, with the submarine threat still even greater, Scientific American published an article (somewhat exasperated in tone) titled “Ideas That Will Not Work.”

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Our full archive of the war, called Scientific American Chronicles: World War I, has many articles from 1914–1918 on naval warfare. It is available for purchase at www.scientificamerican.com/products/world-war-i/