France, after losing 1.7 million of their citizens in World War I, finally emerged victorious but traumatized. They were scared to death the Germans would some day re-militarize and attack again. To prepare for this eventuality they built a 450-mile-long, 15-mile deep series of interconnected fortifications, known as the Maginot Line, with its fixed-in-place guns pointed toward Germany. It stopped short of the Ardennes forest as that was considered an impenetrable natural obstacle. Their only unguarded eastern border was with Belgium, where the French planned to mass their forces if the Germans were to ever attack via that route. They were feeling pretty secure.
While the Maginot Line looked formidable, a few enlightened military leaders of the time, among them Charles de Gaulle, thought differently. They preferred a more mobile defense centered around tanks and airplanes. They knew if the Germans should break through at any one point, they could react and respond quickly. Their view did not prevail.
On May 10, 1940 France's worst fear came true, in spades. The Germans attacked, but not directly toward the Maginot Line, which the French were prepared for, or through Belgium, where the French had troops poised to defend, but through the supposedly natural barrier of the Ardennes forest. The Germans punched through, then swung north to outflank the French and British Expeditionary Force (did you see the movie Dunkirk?), and south where they came in BEHIND the Maginot Line with its immovable guns pointed in the wrong direction. Game, set, match. The French defenses folded like a card table.
Fast forward 78 years and now it's the United States concerned about its southern border, and rightly so. Drug smugglers, gun runners, human traffickers, and others have their eyes on us. They want in. The border security system we have now is only marginally effective. Those who say we need something more are completely correct. But as history should have taught us, those who say we need a massive, enormously expensive, fixed-in-place structure are completely wrong.
The Maginot Line didn't work for the French in 1940, and a Trump Wall won't work for the US in 2018. What we need is security that is maneuverable, strong, and fast reacting. Imagine, for example, a sizeable fleet of small manned patrol aircraft, and many more drones than we have now, too, backed up with the ability to very rapidly bring in overwhelming manpower anywhere along our border to deal with any intruders.
Our adversaries are smart. State-of-the-art security measures that might work today will likely prove to be laughable just a few years from now. That's how fast technology is changing. The Maginot Line became a metaphor for expensive efforts that offer a false sense of security. Let's not make that same mistake all over again with a tall, low-tech wall. Let's be smart for once.