And they were trenchmates.
Aw, you got a snort out of me. Well done.
What was the 2nd little hole for?
Airflow
Just a guess, but if someone steps over it, the light from that small hole is covered, so the occupants of the hole know to squeeze into the corner so they wont be seen if someone peers down into the hole.
Not sure. Ventilation?
I would guess an inlet for a small fire, like an igloo.
A
I guess hand grenades weren’t invented yet?
Not of the efficient sort you’re thinking of, probably! Lit improvised grenades were still in intermittent use, but the modern grenades we’re familiar with wouldn’t come about until the First World War, about 15 years after this.
Grenadiers were really common in the 18th and early 19th century, over a hundred years before the Boer war. They started appearing in the late 17th century even. They used tennisball-to-hockeyball-sized iron bombs with manually lit slow fuses. So their job was to walk forward, light fuses and fling 4 pounds of metal and powder towards the enemy. Repeatedly. While getting shot at. There’s a reason the grenadiers were regarded as elite troops. France even had Horse Grenadiers at one point.
There’s also a reason there were a lot less grenadiers when guns started getting better: standing in the open and lighting fuses is not the most survivable things to do when the enemy has rifles instead of muzzle-loading muskets. So yeah, grenades existed, but not until ww1 did they get popular again, as a secondary weapon instead of primary one.
Hence “still in intermittent use”.
Also, grenadiers in the 18th century usually did not use, well, the grenades they were named for. It was always a bit of a niche weapon.
Oh yeah, in the 18th century it was already turning into a honorary title more than a job, but it was still used. Grenades have historically been a “siege weapon” until the 20th century used when storming forts (and one could argue storming trenches is a form of siege warfare too). So yeah, pretty niche, this is exactly that kind of niche.
There’s even the famous song about throwing grenades from the glacis (meaning the exterior slope of a (star)fort) at the enemy, and it’s from the early 1700’s.