There were persistent rumors in the Middle Ages about communicating with magically magnetized needles that would move in sync over hundreds of miles. It was so obviously useful -- and a handy way to explain some statesmen's skills, with knowledge from far off.
Still, the effect on government was obvious.
The last cause of this disobedient spirit in the Colonies is hardly less powerful than the rest, as it is not merely moral, but laid deep in the natural constitution of things. Three thousand miles of ocean lie between you and them. No contrivance can prevent the effect of this distance in weakening government. Seas roll, and months pass, between the order and the execution, and the want of a speedy explanation of a single point is enough to defeat a whole system. You have, indeed, winged ministers of vengeance, who carry your bolts in their pounces to the remotest verge of the sea. But there a power steps in that limits the arrogance of raging passions and furious elements, and says, SO FAR SHALL THOU GO, AND NO FARTHER. Who are you, that you should fret and rage, and bite the chains of nature? Nothing worse happens to you than does to all nations who have extensive empire; and it happens in all the forms into which empire can be thrown. In large bodies the circulation of power must be less vigorous at the extremities. Nature has said it. The Turk cannot govern Egypt and Arabia and Kurdistan as he governs Thrace; nor has he the same dominion in Crimea and Algiers which he has at Brusa and Smyrna. Despotism itself is obliged to truck and huckster. The Sultan gets such obedience as he can. He governs with a loose rein, that he may govern at all; and the whole of the force and vigor of his authority in his centre is derived from a prudent relaxation in all his borders. Spain, in her provinces, is, perhaps, not so well obeyed as you are in yours. She complies, too; she submits; she watches times. This is the immutable condition, the eternal law of extensive and detached empire.
It had its effect on the men sent out there too. The British Empire was mightily changed by the telegraph, when the men on the field could get their orders in an instant from Britain. They could no longer care out the grand, sweeping deeds for which they became famous, when they were off the leash.
Took a while, to be sure. Even the telegraph did not prevent Grant from serenely ignoring some orders in the American Civil War and arguing that they were so obviously based on out-of-date info that obviously he should have, to fit the current situation. On the other hand, people could appeal to the White House to get an order of his overruled within the hours necessary to prevent its being a problem, so it was starting. The 19th century was an era of great change, even if it was not to reach the communicative heights we got today.
To be sure, send your colonists over the depths of space, with an FTL drive but no FTL communicators, and you revert to a pre-19th century situation. And in an earlier one, anything equivalent to those magnetic needles would be powerful indeed, especially with the concentrated ability.
Not something many world-builders deeply concern themselves with.