Nearby ship could have helped
The Leyland liner Californian, bound in April 1912 from London to Boston, with room for forty-seven  passengers but carrying none at the time, was close enough to receive wireless messages from the foundering Titanic and to help in a rescue . But the Californian's radio operator was not on duty. He had had no relief, and had to sleep sometime.

Columbus
Columbus was on the road out of  Spain and on his way to Paris for financial backing in early 1492, when a messenger overtook him with news that the Spanish King Ferdinand had changed his mind and would finance a westward voyage to India.

How communications has improved
It took five months to get word back to Queen Isabella about the voyage of  Columbus, two weeks for Europe to hear about Lincoln's assassination, and only 1.3 seconds to get the word from Neil Armstrong that man can walk on the moon.

Eiffel Tower could have been demolished
Paris's best --known monument, the Eiffel Tower, was saved from demolition in 1909 because there was an antenna , of great importance to French radio telegraphy, mounted at the top of the nearly 1,000-foot-high structure.