> I’m not sure how apocryphal this is but apparently, soldiers would often walk arm in arm, or hand in hand.

Men still do in many cultures - I remember being surprised by it the first time I went to Turkey but it rapidly becomes no big deal. If you tried that amongst the general public here (UK) you'd definitely get funny looks and could be in danger of getting beaten up.

Indeed. Gender is a societal construct but it is often difficult to perceive when you are embedded in that society.