Assault, a highly decorated thoroughbred and winner of the Triple Crown, was born at the King Ranch on March 26, 1943. He was the foal of Bold Venture and Igual. His sire, Bold Venture, winner of the Kentucky Derby and the Preakness Stakes in 1936, was directly related to Commando, the 1900 and 1901 Horse of the Year. His broodmare sire was Equipoise, the 1932 and 1933 Horse of the Year. As a colt Assault was injured when a surveyor's stake split his front right hoof. The deformed hoof caused Assault to walk with a limp, but he showed no signs of injury at a gallop. The malformation gave Assault his nickname—the "Clubfooted Comet." Owner Robert J. Kleberg, Jr. employed Max Hirsch to train Assault. Hirsch, raised on the Morris Ranch near Fredericksburg, had also trained Bold Venture.
As a two-year-old Assault began his racing career with a disappointing twelfth place finish. In the Flash Stakes at Belmont Park, Assault, who was listed as a seventy-to-one underdog, claimed victory in a four-way photo finish. Assault entered nine races as a two-year-old, winning twice, placing second twice, and claiming third place on one occasion.
Assault began his season as a three-year-old by winning the Experimental Free Handicap and the Wood Memorial Stakes, both held in Jamaica, New York. At the 1946 Kentucky Derby the sixth-seeded Assault overcame eight-to-one odds in a seventeen horse field, winning by eight lengths. It was the widest winning margin in Derby history. The dark chestnut colt, ridden by jockey Warren Mehrtens, was the first Texas-bred horse to win the Derby.
Although Assault's time of 2:06 3/5 was relatively slow, having finished more than five seconds behind the Derby record, it was enough to make him the favorite in the Preakness Stakes in Baltimore a week later. There he had fallen to the sixth position in a field of ten horses, but at the top of the stretch he had moved four lengths ahead of the pack. As Assault began to tire, Lord Boswell made a final push towards the finish line. Assault held on to win by a neck but led many to question if he could hold the lead in long distance races. Assault met Lord Boswell again at the final stage of the Triple Crown, the Belmont Stakes in Elmont, New York, on June 1, 1945. The Belmont, which was five-sixteenths of a mile longer than the Preakness, listed Lord Boswell as the favorite, with Assault given odds at seven-to-five. Two hundred yards from the finish line Assault, who had been as much as eight lengths behind after stumbling out of the gate, bolted to the front and captured the win by three lengths. With this win Assault became the seventh horse to claim the Triple Crown.
Assault won the Dwyer Stakes at Belmont Park two weeks later, although his slow time led many to believe he was merely the best horse in a poor group of three-year-olds. The winning streak came to an end after Assault finished last at the Arlington Classic, although his poor performance was attributed to a kidney infection that was diagnosed a few days later. After six weeks away from the track Assault failed to secure a win in his next five races, finishing second at the Jersey Handicap and the Roamer Handicap and third at the Discovery Handicap, Manhattan Handicap, and the Gallant Fox Handicap. It was not until the Pimlico Special in Baltimore that he made an exciting run to claim his first victory since the Dwyer Stakes. Assault finished his season by winning the Westchester Handicap by two lengths. Although he had a losing streak of six races, the Triple Crown and the win at the Pimlico Special was enough for Assault to be named both Champion Horse of the Year and Champion Three-Year-Old Colt in 1946. He was also the leading money winner of the year, earning $424,195 with eight wins out of fifteen starts.
Assault began the 1947 season with wins at the Grey Lag Handicap, the Dixie Handicap, Suburban Handicap, the Brooklyn Handicap, and the Butler Handicap. The winning streak came to an end when Assault placed third at the International Gold Cup at Belmont Park. A charity match race for $100,000 was arranged between Assault and the six-year-old Armed who would later be named the 1947 Horse of the Year. The race was postponed four weeks until September 27 after Assault was injured by a nail in his shoe. Less than a week before the race, Assault returned lame from a workout. Assault lost the race by eight lengths, although many, including Assault's jockey, felt the horse was not in shape to race.
After his four-year-old season Assault was retired to the King Ranch in 1948 and turned out to stud, but it soon became clear that he was sterile. Assault returned to the track as a five, six, and seven-year-old, but was not able to capture wins as easily as he had during his younger days. He won his last race on November 22, 1950, at Hollywood Park. During his career Assault won eighteen out of forty-two races, placed second six times, and came in third on seven occasions. With wins totaling $675,470 Assault was one of the leading money earners of his time. Assault was inducted into the National Museum of Racing and Hall of Fame in 1964. In 1999 a panel for Blood-Horse Magazine ranked Assault number thirty-three on their list of the top 100 racehorses of the twentieth century. Assault passed away on September 2, 1971. He is buried at the King Ranch. Also known as the "Texas Flier" and "Texas Terror," Assault stood 15.3 hands tall and sported the markings of a forehead star and one white sock. Though assessed as average-looking by many in the racing establishment, the horse remained the only Texas-bred Triple Crown winner as of the early twenty-first century.