The song was about William Pembroke Mulchinock and Mary O'Connor.

There are a couple versions of the song's story

William was involved (not directly) with a murder at an election meeting in Tralee, and then took off to be a war correspondent in India. It was at the time of the Indian mutiny. When he came back to Tralee, he was having a drink one day when a funeral passed. It was Mary O'Connor's. He then married someone else and went to America. The marriage broke up, he returned to Tralee and was buried beside Mary.

Alternatively, Mulchinock's father was of high rank in the British Army and regarded his son's love affair with Mary O'Connor as a scandal. He arranged for his son to be posted to India where William was severely injured and blinded when a field gun exploded. Mary O'Connor died of a broken heart not knowing what had happened to her William.

The pure crystal fountain is at Skannagh Cross, which I presume is near Tralee.

I found the third verse in an old magazine.

Regards Mick Bracken