The fact they stubbornly held on as long as they did, with as little as they had. There's the famous myth of cavalry units charging against tanks.
Originally Posted by cogdecree
And even then, they refused to give up. Whether it was with Polish units fighting with the Allied forces in the Western campaigns or in the resistance at home. This was especially seen during the '44 uprising in Warsaw.
It's all part of the general Polish traditional sense of heroism, which is summed up in the first verse of the Polish anthem:
Poland has not perished yet
So long as we still live
That which alien force has seized
We at sabrepoint shall retrieve
To specify, I'd say INFX.