Ah, but that doesn't tell the whole story, does it?
It all started in the Russo-Japanese war. The Japanese were short on manpower and they would recruit pretty much anybody as a sailor. Since the work on the turrets was very dangerous, they'd leave that for the less valuable men.
Two weeks into the war Togo decided to recruit Ninjas to work on the turrets but they refused to touch the Navy's uniform and prefered to remain in their black battle suits. A few of them also got to man the guns on Merchants and when the Russians discovered them after capturing a Merchant they adopted the idea.
American, Canadian and other Merchants that also got in contact with the Ninjas decided to copy the hood too. And from then on more and more Navies "Ninjafied" their gun crews.
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PS:
