War Admiral (May 2, 1934 -- October 30, 1959) was an American thoroughbred racehorse, best known as the fourth winner of the American Triple Crown and Horse of the Year in 1937, and rival of Seabiscuit in the' Match Race of the Century' in 1938. During his career toward the end of the Great Depression, War Admiral won 21 of his 26 starts with earnings of $273,240 ($3.5 million in 2016 dollars.) After his retirement stud, he was the leading sire in North America for 1945 and was also an outstanding broodmare sire whose influence is still felt today in descendants such as American Pharoah.

When did war admiral win the triple crown? OK. Let's think. My stream of consciousness:
The relevant information to answer the above question is: War Admiral (May 2, 1934 -- October 30, 1959) was an American thoroughbred racehorse, best known as the fourth winner of the American Triple Crown and Horse of the Year in 1937, and rival of Seabiscuit in the' Match Race of the Century' in 1938. The answer is 1937.