Which American President lost his son in a train accident just prior to his inauguration?

On January 6, 1853, weeks after winning the 1852 presidential election, Franklin Pierce and his family were involved in a train derailment near Andover, New Hampshire. Franklin and Jane Pierce survived, but their 11 year old son, Benjamin, was crushed to death, nearly decapitated. The horrified parents witnessed the gruesome scene. Having already lost two sons, they entered the White House in mourning.

Hailing from New Hampshire, Pierce showed early promise though born in a log cabin. Pierce's father, who had served in the Revolution, was a farmer and tavern keeper. He later became prominent in state politics. His father determined to see his sons educated, sent Pierce to Bowdoin College, where he began a life-long friendship with classmate, Nathanial Hawthorne. Emulating his father, Pierce served in the Mexican War as a brigadier general. Also, like his father, Pierce entered politics serving as a Congressman, Senator, and eventually President.

Plagued by demons, Pierce was a heavy drinker all his life. His wife suffered from depression, exacerbated by the death of her children. Pierce's term was disastrous. He was the only sitting elected President seeking reelection not to be renominated by his party.

He died in 1869 of cirrhosis of the liver at the age of 64. Jane had predeceased him on December 3, 1863 of tuberculosis.