As discussed in my new book, ASSASSINATIONS, THREATS, AND THE AMERICAN PRESIDENCY: FROM ANDREW JACKSON TO BARACK OBAMA, in two of our tragic assassinations of American Presidents, there are three, relatively unknown, potential Presidents who could have emerged.
Two of these individuals are relevant to the Abraham Lincoln Assassination–President Pro Tempore, Senator Lafayette Foster, of Connecticut; and Vice President Hannibal Hamlin.
IF Vice President Andrew Johnson had been killed when Lincoln was, on April 14, 1865, as he was supposed to be under the John Wilkes Booth plot against the US Government, the next in line under the Presidential Succession Act of 1792 would have been Lafayette Foster, an obscure member of the Senate.
IF Lincoln had not replaced first time Vice President Hannibal Hamlin with Andrew Johnson, Hamlin would have become President, instead of Johnson.
Also, when William McKinley was assassinated in 1901, Vice President Theodore Roosevelt, only six months in office, succeeded him, but IF first term Vice President Garret Hobart had not died in office of heart disease in 1899, it is likely he would have been Vice President in the second term, and would, therefore, have become President. We might not even know who Theodore Roosevelt was, as simply a New York Governor, but not of national significance, other than his role in the Spanish American War as a “Rough Rider” in Cuba.
So these three “unknown” potential Presidents–Lafayette Foster, Hannibal Hamlin, and Garret Hobart—remain in relative obscurity in history, and Andrew Johnson and Theodore Roosevelt became famous!