Jordan, super cool pics, thanks for posting. Really like looking at the details of weapons these guys have, its always cool going over pics with a fine toothcomb, its amazing the details you can notice.
Question on the artillery pics...for example Picture 3 of group 1, you say a 75mm Artillery Squad...does it say 75mm on the back? Just spitballing, but look at the wheels on the carriage, they are very big, almost as tall as the guy standing next to it, and the height of the gun shield is well taller than the men, that's a big gun. Also look at the two rounds standing against the sandbag walls, look big for 75's....
I am not really up on WWI German arty pieces, I'd have tio do some research, but I am guessing it may be a 10,5 cm gun...
Picture 1 in group 2 is also really cool, very clear. Again, I am thinking bigger than 75, look at the size of the breech ring hole compared to the guys fist...could be just from the optical angle, but looks a bit bigger than his fist, and a fist is about the same size as a typical 75mm base, so this too seems bigger, maybe 10cm...I'll see if I can find any candidates.
Another cool thing on the pic is notice the Rundblickfernrohr (panoramic telescope) laying scope in its mount on the left side of the gun. This is the standard sighting unit for indirect fire guns. While it can be used for direct fire, it usually is used to shoot back azimuths to aiming stakes (the red and white striped poles you see a lot of times in pics of German artillery) in order to properly lay the guns. Also you will notice in the pics of one I will post they are painted with a bright orange on the top section. This was so the gunners have a easily visible target to sight other guns with so they can determine the exact relationship to other guns, to compensate for variations of elevation and direction between guns, so when battery fires as a battery they can correct against the other guns so they are all firing at the same point, or correct separation as is required. If you look at the rotating optic head on it in the picture, you can see its actually pointing back behind the gun, likely because it was used to sight the aiming stakes behind it.
The scopes locked into the mounts, but were removeable, and were stored in a special box mounted to the gun when not needed to protect them.
The Rundblickfernrohr design stayed basically the same from WWI through WWII, and many WWI scopes were used in WWII (Rundblickfernrohr 16's and 18's). In fact the scope in my pics is a WWI scope....the mount is for a sFH 18 15cm gun in a SP mount (the Hummel)…