not sure about any battle, but the sarovar around harmandir sahib was a lake in a dense forest area i believe.
iv heard that Guru Nanak Dev ji visited this place and that buddha did too
I think Guru Amar Das ji chose the location while Guru Ram Das ji made the lake into a sarovar and started a city which late became Amritsar
During the time of Guru Ram Das ji bibi Rajni visted the sarovar with her sick husband and saw crows flying into it and coming out as doves, Her husband also went into the sarovar and came out free from his disease. The part of the sarovar that this happened in is where dukh bhanjani beri is. I think Bibi Rajni visited when it was still a forest and not a city yet ...
other than that i dont know more ...
a few years back i watched this jewish mans story, it was about how he died saw the after life and then came back again and changed. similar to how you hear sikhs who died and came back again and they saw jamdoots and dharmraj etc.
he went to the next world and i think he only saw jewish men and women, no mention of jamdoots etc
its interesting how these experiences are different depending on your faith.