Ammon News - The first successful transatlantic telegraph exchange between heads of state occurred on this day in 1858.
Queen Victoria sent the first message—“The Queen desires to congratulate the President upon the successful completion of this great international work”—to U.S. Pres. James Buchanan.
Though nearly instantaneous by 19th-century standards, the transmission took more than 16 hours.
Unfortunately, the cable went dead on September 1, and a working cable was not available until 1866.
Britannica