Man o' War (March 29, 1917 - November 1, 1947) was an American Thoroughbred who is widely considered one of the greatest racehorses of all time. During his career just after World War I, he won 20 of 21 races and $249,465 (equal to $3,047,451 today) in purses. He was the unofficial 1920 American horse of the year and was honored with Babe Ruth as the outstanding athlete of the year by The New York Times. He was inducted into the National Museum of Racing and Hall of Fame in 1957.

Man o' War was inducted into the National Museum of Racing and Hall of Fame in 1957. In 1959, the Man o' War Stakes was created in his honor. In the Blood-Horse magazine ranking of the top 100 U.S. Thoroughbred champions of the 20th Century, Man o' War was ranked No. 1. He was also ranked No. 1 by the Associated Press as the greatest horse of the 20th century in a separate poll. He was also ranked No. 1 greatest horse in racing history by Sports Illustrated (panel of 7) in 1992. ESPN ranked Man o' War as number 84 on their list of the top athletes of the 20th century. There is a roadside historical marker at the location of his birthplace in Lexington (Nursery Stud), though the site has since been redeveloped. The stallion barn at Faraway Farm where he spent most of his life was renovated in the early 2000s - it is now part of Mt. Brilliant Farm. His stall door was loaned to the National Museum of Racing and Hall of Fame in Saratoga as part a special exhibit, "Man o' War at 100", that opened on March 29, 2017. Glen Riddle Farm in Maryland was home to Man o' War during the off seasons of his racing career. The land was redeveloped in the early 2000s as GlenRiddle, a gated community with two golf courses, one of which is named in Man o' War's honor. The barn in which Man o' War stayed was converted into the golf clubhouse. In the 1950s, the Riddle estate sold the property Riddle had owned in Glen Riddle, Pennsylvania, which became the Riddlewood housing development. One of the roads in Riddlewood is named Man o' War Drive, another is War Admiral Lane. Man o' War Boulevard, a major arterial that circles to the south of Lexington, is also named in the horse's honor. Central of Georgia Railway once ran a Man o' War passenger train between Atlanta and Columbus.

Using a quote from the above article, answer the following question: what was the best rank?
ranked No. 1