Her mother was frequently ill and ill-disposed to travel and socializing, and chose to remain at home in Auburn while her Seward's served in the Senate and the cabinet.

When her father began his term as Secretary of State in 1861, Seward, then sixteen, resided with him in Washington, D.C. and became his closest domestic companion.

She is best known for keeping a voluminous diary throughout the course of the Civil War, which documented with intimate detail the social and political milieu of Washington during the Lincoln administration.

[5] On the night of April 14, 1865, Lewis Powell, an associate and co-conspirator of John Wilkes Booth, attempted to assassinate Seward at his Washington D.C.

[11] Now certain of William Seward's location, Powell pretended to leave and started down the stairs, but suddenly turned around, drew a pistol, and pointed it at Frederick's head.

[15] Powell burst through the door, threw Fanny Seward to the side, and jumped on the Secretary's bed, repeatedly stabbing him in the face and neck area.

[16] Outside the home, David Herold, who could hear the screams coming from the house, fled with both horses, leaving Powell to fend for himself.

All five men that were injured that night survived, although Secretary Seward would carry facial scars from the attack for the rest of his life.