---
title: "Telegraph Line Opens London-Paris"
year: 1851
country: "United Kingdom"
canonical: "https://recap.at/1851/telegraph-london-paris"
slug: "telegraph-london-paris"
recapType: "global_event"
startDate: "1851-01-01"
---

# Telegraph Line Opens London-Paris

> The first submarine telegraph cable connecting Britain and France inaugurated instantaneous long-distance communication across international borders.

On August 13, 1851, the first submarine telegraph cable connecting London and Paris went live, allowing messages to cross the English Channel in seconds for the first time. The 21-mile cable, laid by the British and French governments, reduced communication between the two capitals from hours by courier to near-instant electrical transmission. It proved submarine telegraphy was viable and sparked a global race to wire the world.

## Summary

Electrical telegraphy is point-to-point distance communicating via sending electric signals over wire, a system primarily used from the 1840s until the late 20th century. It was the first electrical telecommunications system and the most widely used of a number of early messaging systems called telegraphs, that were devised to send text messages more quickly than physically carrying them. Electrical telegraphy can be considered the first example of electrical engineering.

## Key facts

- **Cable length**: 21 miles across the English Channel
- **Launch date**: August 13, 1851
- **Message transmission time**: Near-instantaneous (vs. hours by courier)
- **Countries involved**: United Kingdom and France
- **Cable depth**: Maximum 300 feet below sea level

## Timeline

- **1844-01-01** - Telegraph established in Britain
  Samuel Morse's telegraph system becomes operational in the United States; British engineers begin adapting the technology.
- **1848-01-01** - Submarine cable experiments begin
  William O'Shaughnessy and others conduct early trials with insulated cables submerged in water to test signal transmission.
- **1851-08-13** - London-Paris cable goes live
  The 21-mile submarine telegraph cable across the English Channel successfully transmits its first messages between London and Paris.
- **1858-07-27** - Transatlantic cable operational
  The first successful transatlantic telegraph cable links Valentia Island in Ireland to Newfoundland, enabling London-New York communication.
- **1870-01-01** - Global submarine cable network accelerates
  Multiple submarine cables connect Europe to Asia, Africa, and Australia, establishing the foundation for worldwide telegraphy.

## Impact

The successful crossing of the English Channel by telegraph cable demonstrated that electrical communication could operate reliably underwater over significant distances. This vindication of submarine cable technology unlocked decades of international infrastructure investment, eventually enabling global communication networks that reshaped commerce, diplomacy, and news distribution.

## Sources

- [Telegraph line](https://en.wikipedia.org/wiki/Electrical_telegraph) - Wikipedia

---
Canonical: https://recap.at/1851/telegraph-london-paris