There is a military benefit to color blindness.
My maternal Grandfather was an Infantry Captain at the end of WWII. He was severely color-blind, though I don’t believe it was complete (seeing only shades of gray). When he was drafted, being colorblind was a disqualification to being commissioned as an officer.
But the Army learned that he had a use in particular because of his “deficient” vision. The camouflage netting and techniques of the enemy didn’t work on his eyes. His perception wasn’t keyed to the colors. They would take him in boats and aircraft to scout enemy positions.
He did eventually, I’m told by making a nuisance of himself, get the powers that be to let him take the Officer Candidate Battery, and scored so high on it that they couldn’t turn him down for a commission.
As a newly minted 2LT, he joined his unit (2/10th Infantry, 5th Infantry Division), and was shocked to find people scurrying for foxholes and shelters looking at their watches. He was hustled to a shelter and informed that the Germans were shelling on a time table and there was a German artillery position in the woods nearby that was pounding the position, but a very regular intervals.
After the shelling ended, he approached his company commander and asked permission to “borrow” an artillery battery (while enlisted, he’d been trained as an artilleryman) and that he’d take the gun out. The CPT was dubious but let my Grandfather try it. It took two rounds, but he did destroy the German gun.
The Germans had draped their cammo nets over the barrel of the gun and run it straight up to vertical, giving it the cone shaped appearance of the surrounding evergreen trees. Or gave that appearance to every one but my Granddad. He’d quickly spotted it after the shelling.
My color blindness is not so severe. I’m red-green colorblind, meaning that that is the part of the spectrum that I lack the regular quantities of “cone” receptors for. I have little concept of Purple, for example and tend to see either blue or red. What you call red I often see as brown. The brown t-shirt that is part of my uniform, I see as green.
And US military camouflage nets on their woodland side, in comparison to natural foliage, I see as orange.
While driving my Platoon Sergeant around on Fort Chaffee at Annual Training one year, I noticed some “orange” blobs in the treeline. A little looking and I knew who it was.
“SFC King, the 160th has a battery out here.”
“What? Where is that?”
“Back there in the treeline.”
Much pointing followed and he didn’t see them. Eventually, he had me back up and show him. He still didn’t see them from the road. So we walked up on them and at about 75 meters he was finally able to make out the 105s under the netting. I’d made them out from better than twice that distance from a moving vehicle while driving.