I am Belarusian and live not far from the pre-1939 Polish-Soviet border. In 2012, while cycling along a forest road I saw a strange granite slab with some Polish text inscribed. The slab looked at least several decades old and had indentations, which appeared to be made by bullets or shrapnel. Here are characters that I was able to make out:
Gro__a
WykonanaPrzez
Ocho__cza
DruzyneRobocza
___6
w 1936 r.
The underscore marks represent the unreadable characters. I don't speak Polish so I had no I idea what might they be or what the whole text meant (apart from "w 1936 r.", which obviously means "in 1936").
I already posted this question on another forum back in 2012, which came up when I was googling some Polish names. That forum, apparently, had very small community, so the only reply I got was from its admin who also has an account here as zefir454. Turns out that zefir454 or Józek, as he signs his posts, for some reason reposted my question here as "Mysterious Monument in Belarussian.", rather than simply inviting me to this larger forum with an English-language section.
Communication with zefir454 was always very difficult due to the language barrier (Polish is, basically, the only language he speaks and I don't speak Polish), for that same reason the thread he started here as "Mysterious Monument in Belarussian." with my question is badly messed up, since he had very dim understanding of what I originally asked and so, as far as I can see, steered the conversation the wrong way. Besides it's completely in Polish, so even with GoogleTranslate I don't understand much.
Because of all that plus the fact that zefir454's forum is very unreliable (look at my 2012 thread, all my posts had vanished, but his remain and he doesn't know why), I decided to start a new thread when I accidentally found out about this forum (via Google, too).
One more (and hopefully the last) thing off topic, when looking at zefir454's thread with my question, I noticed that some of the other posters thought it was weird for a Pole and a Belarusian to communicate in English. Well, I don't know what it is that you expect from me, but I can assure you that while it might be weird for a Belarusian to speak good English, it's a lot more weird for a Belarusian who lives 100+ kilometers from the current border with Poland to speak any Polish, so I decided to use English as the one and only international language. Anyone who can help me, but only speaks Polish is welcome to use GoogleTranslate to translate my question and answer in Polish. Hopefully another user will be willing to retell his answer to me.
And now that I finished with off topic, hopefully sorting out the mess created by zefir454 in the process, let's move on to the relevant things. Below is an up-close photo of that slab, which presents a relatively good view.

I didn't take any photos when I first saw that slab, so it was taken in 2013, nothing had changed about it, though. Links to three more photos, one from a greater distance, one from a different angle and one identical to the photo above but with minimal compression are below.
http://img4.imagetitan.com/img.php?imag ... ge(01).jpg
http://img4.imagetitan.com/img.php?imag ... ge(02).jpg
http://img4.imagetitan.com/img.php?imag ... ge(03).jpg
From what I gathered of zefir454's replies on his forum, I assumed that the original text was "Grobowca wykonana przez ochotnicza drużyne robocza", am I correct? If yes, can anyone translate into English? Also, from what I understood reading zefir454's thread here and links in it through GoogleTranslate, it seems that "ochotnicza drużyne robocza" refers to a specific organization. Can anyone tell me more about the organization, hopefully shedding some light onto what exactly is that thing they built and why they built it?
