Transatlantic telegraph cable

Fog over Heart's Content

Having paid out cable westward from Ireland, Great Eastern reached Heart's Content in Trinity Bay, Newfoundland, on a foggy morning on 27 July 1866. At about eight the fog lifted.

Around nine the expedition cut the deep-sea cable and arranged for Medway to connect and land the shore end. That was done around midday, completing a working telegraph link between Europe and the existing North American networks.

The Times came through first

Before the shore end was down, the ship received text from that morning's London Times through the cable, demonstrating electrical continuity all the way back to Ireland.

Cyrus Field, who had carried the project through repeated failures, went ashore at Heart's Content. His arrival message reported that everyone was well and the cable in perfect working order.

One cable, and one day early

This was not the first Atlantic cable. The 1858 line carried messages for about three weeks before failing, and expeditions had already failed in 1857.

Nor was the lost 1865 cable recovered on 27 July: Great Eastern grappled it on 2 September and completed that second connection in September, so this day did not leave two working lines.

If "put into service" means opened for public business, 27 July is a day early — the cable was completed and tested then, and public traffic began on 28 July.