[teshigahara]

If you can't read the signs how would you know it's right-to-left? You are only seeing two unknown characters, you don't know which comes first. It's not about vertical vs horizontal. It's that someone who speaks English would assume that all of these signs they can't read are written left-to-right, and write the vertical characters they are copying in the wrong order.

[fenomas]

This is such a facially bizarre thing to contest. They got a Japanese NCO to write the text, and presumably copied it as he wrote it. Why imagine that the NCO wrote it vertically and the soldiers horizontally? Likewise the article doesn't suggest that anyone thought the sign was written by a native speaker; why even imagine that's a requirement?

I mean, consider this in the abstract - the objections you're making here rest on the implicit assumption that you know more about the realities of life in a Japanese POW camp than TFA's author. (After all, if he fabricated the story about the sign he'd obviously fabricate it so as to be consistent with his experiences in the camp.) Do you really think that premise is more likely than the alternative - that TFA's extremely brief telling of the story simply doesn't include whatever details would answer your objections?

[kybernetikos]

Most likely the circumstance they got the Japanese NCO to write the text in was a conversation about learning Japanese and how to write it too. Nobody is deliberately trying to stop them from learning to write, they are most likely in favour of it, the trickiness was just around avoiding the Japanese running the camp from noticing their interest in workshops specifically. If stroke order is important in this context then I expect the Japanese NCO showing them the characters would have told them and explained the proper order.

[j16sdiz]

You knew it is rtl when you see a paragraph is aligned to right

[teshigahara]

No, this doesn't make sense in the context of Japanese.

One of these signs is written right to left:

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQdiwLY...

https://auctions.afimg.jp/h1085974646/ya/image/h1085974646.2...

Which one is it? There is no way to tell unless you already know the characters. Unless someone could read the existing signs they would almost certainly assume they were left-to-right and make any new sign like that if they only had the characters to copy.