The B-24 was flying high above North Africa.

The crew members, as usual because of the low temperature at high altitude, were wearing fur-line leather jackets and trousers.

Sixie, the ball-turret belly gunner, was curled up tightly in his plexiglas bubble. At least once the 5-foot, 7-inch gunner had gotten frozen into his cramped position and had to be lifted out of the bubble.

Sixie was color blind. When he signed up for the Army Air Corps, he had to pass an eye test: peering at a page of colored dots, you had to make out a number hidden in the colors. He passed the test courtesy of a tall guy behind him who whispered the numbers to Sixie.

Now, though, over North Africa, he was able to make out the lush green of the terrain below.

Except … Well, just now he’d seen a large square area in the green that  wasn’t green, but gray.

“Hey, Tex,” he called to a another crew member. “Did you see that?”

“See what?” said the big Texan.

“That gray square down there,” Sixie said.

Only Sixie had seen the geographical anomaly.

Tex passed the word forward to the pilot.

The pilot thought, as did Sixie and Tex, that a big gray square in the forest was a bit unusual.

So he turned the lumbering B-24 Liberator around and flew back to where Sixie saw the gray in the green. The navigator and bombardier targeted the square area — which, as it turned out, apparently was made up of camouflage overhang — and the pilot ordered them to dump everything they had onto the area.

The area lit up like a fourth of July fireworks show. Explosion after explosion as the bombs detonated what turned out to be one of Field Marshal Erwin Rommel’s biggest ammunition and fuel depots.

Sixie had scored a major strike for the 8th Air Force of the U.S. Army Air Corps over North Africa, thanks to his color blindness.

And that’s how my dad helped save the world.