What drove the assassins? In the early 20th century, it was anarchism. McKinley was killed by anarchist Leon Czolgosz in Buffalo, New York. In 1919, Carlo Valdinaci tried to assassinate Attorney General A. Mitchell Palmer with a bomb on his porch at 2132 R Street. Valdinoci tripped on a wicket and his dynamite bomb exploded prematurely, blasting Carlo’s body parts all over the neighborhood.