The first successful transatlantic telegraph cable was completed in 1866, creating a durable telegraph link between Europe and North America.
The cable was laid by the enormous steamship SS Great Eastern for the Atlantic Telegraph Company. It connected Valentia Island, off Ireland, with Heart's Content in Newfoundland, and the working connection was put into service on 27 July 1866. Messages that had previously taken weeks by ship could now cross the Atlantic in minutes.
The year 1858 is the most common wrong answer because an earlier cable did briefly work. Queen Victoria and US President James Buchanan exchanged ceremonial messages, but the cable's signals rapidly deteriorated and the line failed after only a few weeks. A separate attempt in 1865 also broke before reaching Newfoundland.
The 1866 success followed improvements in cable manufacture, insulation, laying equipment and operating technique. The abandoned 1865 cable was later recovered and completed as a second working line, giving the Atlantic a more reliable communications network and helping inspire the nickname “Victorian Internet.”