Signers - Philip Livingston Mystery Cache

This is a series to celebrate the signers of the Declaration of Independence. Each man put his and his families lifes in great peril by being bold enough to add his name to the document, I want to remember these men for the freedoms we now enjoy.

Philip Livingston (January 15, 1716 – June 12, 1778) was an American merchant and statesman from New York City. He represented New York at the October 1774 First Continental Congress, where he favored imposing economic sanctions upon Great Britain as a way of pressuring the British Parliament to repeal the Intolerable Acts. He was also a delegate to the Second Continental Congress from 1775 to 1778, and signed the Declaration of Independence.

Puzzle:

What year did he marry Christina?

You can validate your puzzle solution with certitude.