Borders are a substitute used by less fortunate lands for the sea and the mountains behind which happier countries shelter. No great civilization has grown and endured except behind the shield of ocean, mountain, or desert.
How different Poland’s history would be if it had a few dozen miles of deep salt water between it and its neighbors. How much trouble might be saved if Israel were an island. Countries with cliffs and churning, white-flecked seas for borders tend not to be partitioned or carted off into captivity, especially if they have the sense to build navies.
It is considered impolite to mention it these days, but Britain’s defiance of Hitler in 1940 owed more to the Channel and the North Sea than it did to the RAF. Salt water was our ultimate weapon, and our sensible respect for it made us hesitate, to Stalin’s fury, to launch any invasion against Hitler’s coastline. D-Day was a very near thing, even with the vast resources, the careful preparation, the brilliant deception. If the weather forecasters had gotten it wrong, the invasion fleet would have been scattered and the Red Army would have liberated Paris sometime in 1946, before driving on to the English Channel to ponder the future. At least it would have stopped there . . .
If a country has no sea, it must come up with a substitute. And that substitute is the guarded border. As a safe Englishman, I have never resented or decried these odd and often expensive structures. I can quite see why people want them.