On April 14, 1865, when he was five years old, Sarah Cook, his nurse along with Mrs. Goldsborough who was Seymour's godmother (the wife of his father's employer) took him to see Our American Cousin at Ford's Theater in Washington, D.C., where they sat in the balcony across the theater from the presidential box. He saw Lincoln come into the box, waving and smiling. Later, "All of a sudden a shot rang out ... and someone in the President's box screamed. I saw Lincoln slumped forward in his seat." Seymour watched John Wilkes Booth jump from the box to the stage. He remembers that, not understanding what had happened to Lincoln, he was very concerned for Booth, who broke his leg in the jump.

In 1954, Seymour gave his account of the assassination to biographer Frances Spatz Leighton.

Two months before his death, Seymour appeared on the February 9, 1956, broadcast of the CBS TV panel show I've Got a Secret. After arriving in New York City he suffered a fall, which left him with a large swollen knot above his right eye. Host Garry Moore, after bringing Seymour on stage, explained that he and the show's producers had urged Seymour to forgo his appearance on the show; that Seymour's doctor had left the choice up to his patient; and that Seymour very much wanted to go on.

During the game, Seymour was first questioned by panelist Bill Cullen, who quickly surmised from Seymour's age that his secret was somehow connected with the American Civil War, then correctly guessed that it had political significance and involved a political figure. Jayne Meadows then guessed that the political figure was Lincoln, and finally that Seymour had witnessed Lincoln's assassination. Because Seymour smoked a pipe rather than cigarettes, the show's sponsor, R. J. Reynolds Tobacco Company gave him a can of Prince Albert pipe tobacco instead of the usual prize of a carton of Winston cigarettes.

https://en.wikipedia.org/wiki/Samuel_J._Seymour

https://rb.gy/hux4si

https://www.veteransnewsreport.com/2019/10/29/i-saw-lincoln-shot/