All I 'know' about my family's role in WW1 is from what little I was told as a child.

My Nan lost a brother at Passchendaele.
Her father, my great grandad, was somewhere over there in his 40s. He got wounded by shrapnel.

I haven't a clue if either 'volunteered'.

Grandad - my dad's father - may have been in the horse artillery,
By my rough calculation, he must have been well in his 30s...
Again, no idea if he was a 'volunteer' ???