John Campbell : Short Biography

Still looking for John Campbell who married Mary Dalton and had at least one son,  John  who was born ca 1852 and emigrated to  Boston  before 1877 when he married  Annie Ahearn(AAhern)  whose family was from Cork.  This John the younger  worked as a  laborer until his death from pthisis, a form of TB, in 1889, at onlyage  37, leaving Annie with 5 children.   Looking to the  names given his children for  clues:  his 2 sons were  Joseph and John.  His  3 daughters were Mary, Agnes  and Ann. 

Boston was teeming with  Irish  men and women who came to America for a better life.  They didn't always have the best of things and they died leaving little to no footprint  but..they left children.  This John the younger has hundreds of descendants, people who have achieved  all he could have dreamed of and more.  We know what became of him and his descendants, but we have no info on his arrival, his family  or his origins. The only record of his past is the notation  in his 1877 marriage registration naming his parents, John Campbell and Mary Dalton.  

In 15 years of searching I have found only one Irish clue that seems to have all the right names, in an 1851 pension request noting that JohnC. and Mary D, had once resided with his father Frank C.,  in Cavan Co,  There is no clue as to whether or not my g-grandfather born then or a year later, was their son or their grandon, no link to say there is any relation at all.  While Campbell isn't the most numerous surname in Ireland, there are John Campbells aplenty in  Ireland and the US making a straight forward search very confusing and fraught with frustration.             

 If anyone knows of a John Campbell who married a Mary Dalton  perhaps sometime  between  ca 1840 and  1852,  from anywhere in Ireland, PLEASE  leave a  message here to let me know.