General of the Army Dwight D. Eisenhower commanded the battle for Europe — and for the soul of Western civilization — that unfolded over France’s Cotentin Peninsula 75 years ago this morning.

But it was Henry Ford who won it.

For it was America’s Ford-inspired assembly lines — the nation’s vast industrial capacity — that pumped out the ships, planes, guns and gear that made victory in Normandy and beyond not only possible but virtually inevitable.

Nothing like D-Day had ever been seen before and never will be seen again — a righteous undertaking that probably would have been unnecessary had European leadership not quailed before Adolf Hitler’s malign rise in the 1930s.

But when the invasion came, it was awesome.

It has been said, often only half-jokingly, that on June 6, 1944, a man might have hopped across the English Channel on the decks of the 6,939 warships, landing craft and combat-support vessels arrayed before the five invasion beaches as the predawn fog lifted on that historic morning.

By June 6, Allied air forces had long since swept the Luftwaffe from the skies over Western Europe — no invasion would have been possible had they not done so — but 11,500 US and British warplanes went aloft on that day anyway, delivering some 17,000 tons of bombs and reducing key defensive strong points to smoldering ruins.

There were 1.5 million US soldiers stationed in England as the battle began; 156,000 US and British soldiers either crossed the beaches or parachuted into Normandy on the first day — the vanguard of armies of millions that would effectively clear France of Germans by early fall.

This outcome, in retrospect, was preordained, but it surely didn’t seem so on June 6. The Wehrmacht was legendarily ferocious in defense — and thus Eisenhower had prepared a terse statement acknowledging an invasion failure and taking full, personal responsibility for it.

Certainly, very heavy casualties were anticipated.

In the event, “Saving Private Ryan” notwithstanding, the D-Day butcher’s bill was relatively modest — with some 10,000 Allied soldiers killed, wounded or missing. There were 4,500 fatalities — 2,500 of whom were American — but it is no dishonor to Normandy veterans to note that this would have been considered a day off on the Eastern Front.

And it was, in very fundamental ways, the Eastern Front that was at issue on June 6. The Soviet Union had been hemorrhaging blood since Germany’s invasion three years earlier — and Joseph Stalin had been demanding a second front in Western Europe to take pressure off his gravely wounded nation almost as soon as Hitler declared war on the US on Dec. 11, 1941.

US Army Chief of Staff George C. Marshall also favored an early attack in northwestern Europe; the British, still traumatized by the trenches of 1914-1918, strongly opposed this — producing strategic friction that continued for most of the war.

Still, a successful early invasion would have been close to impossible anyway.

First, America’s assembly lines — its astonishing capacity to produce beans, bullets, bombs and the ships to deliver them — had to be brought up to speed. And so they were.

Simultaneously, the near-existential ­U-boat threat — Germany had been sinking Allied shipping faster than it could be replaced — had to be eliminated. And so the Battle of the Atlantic was prosecuted to victory by May 1943. Only then could invasion preparations proceed.

They did, in spades, and 10 months after D-Day, in the smoking wreckage of Berlin, Adolf Hitler committed suicide and Germany soon surrendered.

Is there contemporary relevance in all this? The likelihood of massed tanks slashing across Europe is quite remote, reducing the need for response in kind to near zero. And, anyway, modern satellite surveillance and precision munitions have long since rendered the conduct of large-scale industrialized warfare virtually impossible.

But just as times change, so do threats. Today’s Western leaders — relieved of one existential peril by the collapse of the Soviet Union — now must contend with nibble-around-the-edges challenges from Islamic fundamentalism and Chinese encroachments.

These aren’t nearly so dramatic as invading armored columns, but they present a threat that — left to fester and given sufficient time — could prove equally lethal.

So if there is a useful lesson to be taken from D-Day, now 75 years in the world’s rearview mirror, it’s that prevention trumps cure — the latter generally being painful, expensive and, all too often, bloody.

Bob McManus is a contributing editor of the Manhattan Institute’s City Journal.