During WW1 raids were made into enemy trenches specifically for the purpose of capturing enemy soldiers who would be brought back for interrogation. What form, I wonder, did this interrogation take?
I seem to remember hearing on some TV documentary that German documents showed captured British soldiers at the Battle of the Somme (1916) to have been remarkably indiscreet about objectives and tactics, but they didn’t go into whether this was the result of naivety or any sort of pressure. I suspect a fair dose of the former, precisely because of the emphasis laid in WW2 on “name, rank and number only”. It’s not hard to imagine the relief of being behind the lines, out of the battle and being treated, at least initially, to a meal and some comfort, and how that might make some young lad talkative.
Also, although there’s some murk about precisely how genuine contemporary atrocity reports were (some recent investigations suggesting that some weren’t just propaganda), I can’t recall anyone alleging consistent patterns of torture of captured POWs.
Vast majority of soldiers were not long term professionals, and later on were mostly conscripts given a few weeks of rifle training. They would have (and did) sing happily.
More important than soldiers, trench raids would yield maps and orders. In that era almost all orders to forward troops down to Platoon and squad level were written ones, delivered by runners. Code books were also useful. But officers only had them.
WW1 was conducted in a very different way from WW2.
For example the commendable Live & Let Live system:
https://en.wikipedia.org/wiki/Live_and_let_live_(World_War_I)
I have read a great deal about WW1 but I do not recall ever reading of prisoners being tortured or abused to extract information.