Jay was born on February 12, 1841. He was the only son born to John Jay, a lawyer and diplomat, and Eleanor Kingsland Jay. He was the brother of Eleanor Chapman, wife of Henry Grafton Chapman Jr. ; John S. Jay, who died young; Augusta Robinson, wife of Edmund Randolph Robinson ; and Mary Schieffelin, wife of William Henry Schieffelin. His paternal grandparents were Judge William Jay and Augusta Jay. He was the great-grandson of Founding Father John Jay, the 1st Chief Justice of the United States. His maternal grandparents were Eleanor and Hickson Woolman Field. His grandfather was a prominent merchant in New York City. Jay entered Columbia College, graduating in 1859.
Career
Jay, who reportedly inherited his father's anti-slavery views, entered the United States Armyat the beginning of the U.S. Civil War and served throughout the conflict, earning the rank of brevetLieutenant Colonel and serving on the staff of General George Meade, Commander of the Army of the Potomac. Jay fought in the Battles of Gettysburg, Mine Run, Chancellorsville, and Appomattox. After the War ended, Jay returned to Columbia where he entered the law school, graduating in 1868. Upon passing the bar exam, he entered into a partnership with Flamen B. Chandler known as Jay & Chandler and located at 48 Wall Street. Chandler was formerly the partner of Edgar S. Van Winkle, who in turn had been partners with Daniel Webster. Jay focused his extensive practice on important trusts and estates as well as railroad an industrial matters. He was also attorney for James Gordon Bennett Jr., publisher of the New York Herald. Jay also served as the vice president of the New York Herald, president of the New York Cab Company and the Valley Farms Company. He was a director of the Commercial Cable Company and the New York Mortgage and Security Company.
In June 1878, Jay was married to Lucie Oelrichs. Lucie was the daughter of Henry Ferdinand Oelrichs, a leading New York merchant, and Julia Matilda Oelrichs, and the sister of Hermann Oelrichs, and Charles May Oelrichs. Together, they resided at 22 East 72nd Street and the old family estate, known as Bedford House in Katonah, New York. William and Lucie were the parents of:
Julia Jay, a twin who died aged 17.
Eleanor Jay, who married Arthur Iselin, grandson of Adrian Georg Iselin, in 1904.
Through his daughter Eleanor, he was the grandfather of Dorothy Iselin Paschal, the wife of Guy Sherman Paschal; and William Jay Iselin, the father of John Jay Iselin; Arthur Iselin Jr.; and Eleanor Iselin, who married Thomas Frothingham Mason in 1932.