Amen, @livinguktaiwan ...
"One only needs to look at modern-day Russia now, another brave soul lost. Hopefully his sacrifice will not go in vain."
... as it was extraordinary that he elected to return to Russia, after his unbelievable recovery from poisoning. He must have been very clear about what awaited him there.
"Hopefully his sacrifice will not go in vain."
What I have never personally seen anything written about it, was did he return with at least some hope for support from others? And did this brave man die, disappointed by the response?
I don't know. But, it takes us full circle back to a central point of your post here, about this memorial to brave Polish people who were betrayed ...