Hi,
One of my great uncles passed through I.R. 13 during the First World War, he was an Armierungssoldat (construction soldier) and I.R. 13 was his Ersatztruppenteil (no idea how to translate that ).
I don't have a lot of items, but I'll show what I have.
Regards,
Lars
Sauer & Sohn Selbstlade-Pistole 7,65 property marked to Infanterie-Regiment Nr. 13 4. Kompanie weapon number 69
............ but what does the "2" designate? Zug (platoon)?