I think we are looking at the remains of the Soviet invasion of Finland.
Finland and Germany united to repel the Soviet invasion up until the time Finland signed an armistice with the Soviets.
The array of weapons and equipment is evident, and the dates on some of the equipment, 1939 in particular is the right time frame.
Also, from the picture of the map, there is reference to "Tst.Os.Kemppi". Kemppi is a location in Finland and "Tst.Os" is tranlated literally as "Battle Group". JR is translated as an "Infantry Regiment".
I know a great deal of you dislike government intrusion into this type of scenarion, as painful as it is, I believe, since there are human remains involved that some sort of government body should be involved. Maybe they are and this is the result.
Just my NOOB $0.02...