Major John Jordan Jermain (May 20, 1758 – February 17, 1819)[1] served in the Westchester Militia during the American Revolution.
Margaret Sage organized the effort to fund and build the John Jermain Memorial Library in Sag Harbor[2] in honor of her grandfather.
[3] The property was bought at a cost of $10,000, and was directly across from Mrs. Sage's then summer home on Main Street.
The John Jermain Memorial Library was permanently endowed by Mrs. Sage that it might forever be secured to the people of Sag Harbor and vicinity.
She became known as Sag Harbor's greatest benefactor, also providing the village with Pierson High School and Mashashimuet Park.