Why was grants name change?

Ulysses S. Grant's name change occurred due to a mix-up when he applied to the United States Military Academy at West Point. His birth name was Hiram Ulysses Grant, but a clerical error on his application listed him as "Ulysses S. Grant." He decided to keep the name, adopting "S" as a middle initial, which he later said stood for "Sam," after his childhood friend, although it had no official significance. This name became synonymous with his legacy as a prominent Union general and the 18th President of the United States.