How did Franklin Pierce's sons die?

His first son, Franklin Pierce Jr , died as a 3-day old baby. Franklin's second son, Frank Pierce, died of typhus at age 4.

The third son, Benjamin, died at age 11, in a tragic train accident not long before his father became President, January 6.1853. The family on a train pulling out from the station at Andover, NH, when the car they were in developed a bad wheel making it drag and become uncoupled from the traiin. It rolled down an embankment and crashed . Benjy was sitting on a bench behind his parents and was hit by flying debris which cut off the back of his head, killing him instantly. Nobody else was seriously hurt.