General Stud Book
The "American Stud Book", the registration book for American Thoroughbreds, was not founded until 1873, much later than the "General Stud Book", and the rules for registration required only that a horse have five generations of ancestors in the "American Stud Book" or other national stud books, unlike the "General Stud Book" rules. In addition, many breeding records were destroyed during the American Civil War, as fighting during that conflict took place in noted American Thoroughbred breeding centers. The result was that most American Thoroughbreds in 1913 were unable to show an unblemished pedigree according to the "General Stud Book" rules. Adding to the problem was the fact that American horses were beginning to win the big horse races in England, starting with Iroquois, who won the 1881 Epsom Derby.