My ancestor, Hannah Caswell, was one of my brick walls for a long time. She was married to my ancestor, William Slack. I knew his ancestry but, for years, I didn't know hers. I did all the logical and appropriate searches and came up with nothing.
Someone had said the her father was Jonathan Caswell but the only reason I could see was that she had a son named Jonathan Caswell Slack. This was a bit of a clue but certainly not proof. So... I eventually did my search the wrong way. I started with the immigrant ancestor, Thomas Caswell of Taunton, Massachusetts, whose genealogy was published in the Mayflower Descendant. I searched down all of the branches of his family and found several Jonathans who were the right generation to have been Hannah's father. I easily eliminated all but one of them. I found that the remaining Jonathan was a son of Joseph Caswell and Lydia Harding who lived in Middlesex Co., Connecticut. Once I got there, I found Hannah and her family and proceeded to prove the line all the way back to Thomas.
Jonathan Caswell married Margery Markham. Hannah was their daughter. She was baptized in East Hampton, Middlesex, Connecticut on 2 July 1786. Jonathan and Margery and much of Jonathan's family, including Joseph Caswell and Lydia, moved to Otsego Co., New York. That is where Hannah married William Slack on 30 April 1807. William was from Northampton, Massachusetts. He was a land owner in Springfield, Otsego Co. and that is where they lived. They had four children, including my ancestor Philinda Slack who was born 3 January 1809. Their other children were Jonathan Caswell Slack, Levi Slack, and Lewin Slack. Levi and Lewin died in 1812 and I believe Hannah died then also -- but I have not found her grave. (Which means she is a bit of a brick wall -- still!) William took his two living children and went back to Massachusetts to his family. There he was remarried in 1813.
Hannah is not only a descendant of Thomas Caswell but, through her mother, Margery Markham, she descends from the Mayflower three times -- making me a descendant of William Brewster, John Howland, and John Tilley. I thought I didn't have any Mayflower lines and then I got three in one!