While at Columbia, he became Captain in a student corps known as the "College Greens" that helped construct the field works at McGowan's Pass on the heights between Harlem and Manhattanville.

[6] He was at various periods a trustee of the Bible Society, and served on the boards of management of many charitable and educational institutions, besides giving liberally to their support.

[8] Several of de Peyster's addresses were published in pamphlet form, for example The Life and Administration of Richard, Earl of Bellomont, Governor of the Provinces of New York, Massachusetts, and New Hampshire, from 1697 to 1701, which was an address delivered before the New York Historical Society at the celebration of its 75th anniversary on November 18, 1879.

[16] Through his son John, he was the grandfather of three grandsons who all served in the conflict in the Union Army, including John Watts de Peyster Jr. (1841–1873), an aide-de-camp and artillery commander with the Army of the Potomac who mustered out as a brevet brigadier general, Frederic de Peyster III (1842–1874), a Colonel and surgeon, and Johnston Livingston de Peyster (1846–1903), a second lieutenant in charge of a battery of artillery credited with hoisting the first Union flag over the Confederate capitol of Richmond, Virginia, after its fall.

[17][18][19] According to Harper's Weekly:[20] "The venerable Mr. Frederic De Peyster... was a man of singular uprightness and purity of character, a broad philanthropist, and an ardent lover of art and literature.