From the Summary: "The best-known element of signals intelligence during the First World War is work against the operational traffic of armies and navies, centering on cryptanalysis and traffic analysis; however, overwhelmingly its largest form, and the area where it was most frequently used, lay in blockade and economic warfare. This paper will center on Britain's role in this area, but British efforts were simply the main element of an allied system. From the start of the war, France pursued independent, essential, and parallel actions; Italy and Japan were less cooperative and important. When the United States entered the war, it worked with the existing system, and left management of the blockade and censorship of maritime cables to Britain and France."
Federal Depository Library Program Electronic Collection (FDLP/EC) Archive: https://permanent.fdlp.gov/
Center for Cryptologic History Special Series (2015), v.11