In addition to weapons and transportation by steamship, Europeans and Americans had the advantage of telegraph communications. Telegraphs using Morse code became widespread in the U.S., Britain, and Europe during the 1850s, but undersea cables were required to connect the colonies. Before telegraphy, a letter from London took about two weeks to reach New York or Alexandria Egypt, a month to reach Bombay on the west coast of India, six weeks to reach Singapore or Calcutta on the East side of India, two months to get to Shanghai and ten weeks to arrive in Sydney, Australia.

A successful undersea cable line between Britain and the US was completed in 1866, and Britain and India were connected in 1870. Australia was linked to the system in 1872 and a trans-Pacific cable was completed in 1903 linking the U.S. with Hawaii, Guam, and the Philippines. Although telegraphy had been pioneered by Americans like Samuel Morse, the British dominated undersea cable. At the end of the 19th century, Britain owned 24 of the world's 30 cable-laying ships and the British owned and operated 2/3 of the world's cable. During World War I, British telegraph communications were uninterrupted while the British cut German cables, forcing them to rely on wireless radio wave transmissions that were easy to listen to. Figure 6.7.2 shows a chart of transatlantic undersea telegraph cables that expedited communication with Europe and the Americas.