One year after the completion of the first telegraph line - between Washington and Baltimore, in 1844 - the first cables were laid across New York Harbor. Unfortunately, these submarine cables lacked physical durability. The only materials to insulate wires at this time were things like caoutchouc, asphalt, wax or shellac. They did not last long for even short crossings, much less reaching 3,000 miles across an ocean. The discovery of a form of rubber called gutta-percha in Malaya 1843 led to suitable insulations by 1847.
The real beginnings of global submarine cable telegraphy began with a wealthy English merchant family named Brett, that financed a cable crossing the English Channel to France in 1850. That cable failed after only a few messages had been exchanged, and was replaced in September 1851.
Also in the 1850-51 period, former aerial crossings of the Mississippi and Ohio rivers that had been wrecked by floods were replaced with submarine telegraph cables. Development continued in Europe, where by 1852 cables were connecting England, Holland, Germany, Denmark and Sweden, and another connected Italy with Corsica, Sardinia and even across to Africa.
Meanwhile people in America and Europe had a vision of a telegraph cable cross the Atlantic. Many scientists thought it would be impossible to lay a submarine cable over such a long distance, and the US Congress laughed at Samuel Morse when he proposed this idea. However, several people, including British chief physicist Michael Faraday, supported the plan.
Cyrus W. Field, a wealthy New York paper merchant who had retired from active business at the age of 35, was enthusiastic about the idea. He decided to lay a submarine cable from the US to England, and in 1854 he gathered a number of wealthy New Yorkers to join him. This group founded the New York Newfoundland & London Telegraph Company.
After a failure in 1855, the company finished the first section of the transatlantic telegraph between New York and Newfoundland in 1856. In the same year, Field went to England to get more partners. He founded the Atlantic Telegraph Company in London, and the company tried to lay the cable across the ocean from England to Newfoundland.
After two failed attempts in 1857, the third trial in 1858 was successful. The cable worked for four weeks, though never very well, because the insulation leaked and finally broke down.
The failure made it very difficult to start a new project, and the Civil War in the US delayed a new attempt for many years. But during this time, the science of submarine telegraphy was making progress. The British government appointed a commission to investigate the subject, and spent many thousands of pounds in experiments. The result was a clear conviction that it was possible to lay a telegraph cable across the Atlantic.
In 1863, when the scientific and engineering problems were solved, Field began to prepare a new attempt. On July 15, the cable was taken on board of a giant ship - The Great Eastern - in England.
A new trial began. For a week all went well; they had paid out nearly two thousand kilometers of cable, and had only nine hundred kilometers farther to go, when the cable broke and went down to the bottom of the sea. All trials to lift up the cable failed, so a new attempt had to be started on March 31, 1866.
It took just five months from the day the new cable had been manufactured until the first message was transmitted across the Atlantic Ocean. The first functional telegraph line between Europe and America was finished. (info and illustration from University of Applied Sciences, Germany)