Trans-Atlantic Bandwidth: Then and Now


A story in the New York Times this week that the Russian Navy seemed to be menacing the trans-Atlantic telecommunications cables that are so vital to the United States and, indeed, the world attracted significant attention and engendered a good deal of alarm. This seems a very modern problem. However, in 1917, the United States and the British faced a similar problem, as a document in the National Archives shows.

On February 1, 1917, Germany launched unrestricted submarine warfare. Two days later the United States broke off diplomatic relations and began the slide toward war. On February 7, the British post office completed a study of what we would today call trans-Atlantic bandwidth to determine how much telegraph capacity would be available to an American Expeditionary Force that might be sent to France. In this era when the U.S. military blithely slings video-laden PowerPoint briefings back and forth across the NIPRNET (that’s the Internet to you and me), the numbers in this work are startling.

The study observed that were 17 submarine telegraph cables connecting Europe and North America, two of them German. However, seven of the 17 were interrupted and three more were faulty. The overall transmission capacity of this degraded system was about 1.2 million words or 7.8 million letters per week in each direction. Put in today’s terminology, that is very roughly 7.8 megabytes per week each way. Of course, a great deal of that capacity was already spoken for. However, if a significant repair effort were launched, it might be possible to spare a total of some 3.9 megabytes per week each way for the Americans.

In early April, with the American declaration of war just days away, the British shared the study with the United States. The Americans were dismayed. Of course, radio transmissions could take up some of the burden but they realized that this technology, then still in its infancy, could pick up only a tiny proportion of the trans-Atlantic communications burden.

Then things got worse. As Professor Jonathan Winkler tells us in his book Nexus: Strategic Communications and American Security in World War I, in mid-February, a German U-boat cut a series of cables connecting Britain, Portugal, Gibraltar and the Azores. To compound the matter, in the summer of 1917, the German Navy began planning a major offensive against the cables. They equipped submarines with specialized grapples and cutting equipment and in mid-January 1918 launched their effort, which continued as late as September 1918. While the Germans were never able to achieve strategic effects by cutting numerous cables in a short period of time, they did make the bandwidth problem even worse and kept the Allies and Americans constantly on the defensive.

As a result of all this, the U.S. government had to struggle throughout the war to conduct its military, naval, and diplomatic business overseas. The Atlantic cable bottleneck had other strategic implications, as well. Winkler describes in his book how the United States was motivated to invest heavily in radio technology and infrastructure and also to pursue its own network of cables after the war. These efforts helped set the stage for America’s global military, economic, and political dominance of the second half of the 20th century. There was another effect, too. With only a modest ability to communicate with Washington, Gen. John J. Pershing, the commander of the American Expeditionary Forces in France was far more independent of the War Department than his British and French counterparts were of their respective ministries in nearby London and Paris. Perhaps some of the present day conventions of American civil–military relations are due in part to that legacy.

Ultimately, the system adapted to the inadequacies of the trans-Atlantic cable system and the German efforts to exacerbate them. While the United States was unable to operate as it might have wanted during World War I because of the submarine cable problem, it learned and made itself stronger and more resilient. Certainly it will be unpleasant if Russia ever attacks the submarine cable system. However, history gives us some hope that if that does happen, the United States will find a way to adapt and overcome in the long run. With any luck, the foreknowledge of Russia’s potential moves has allowed the United States to already start adapting.


Mark Stout is a Senior Editor at War on the Rocks. He is the Director of the MA Program in Global Security Studies and the Graduate Certificate Program in Intelligence at Johns Hopkins University’s School of Arts and Sciences in Washington, D.C.


Photo credit: Bundesarchiv, DVM 10 Bild-23-63-65 / CC-BY-SA 3.0