Penny Chenery of Meadow Stable bred her mare Somethingroyal in 1969 to the great sire Bold Ruler, owned by Ogden Phipps of Wheatley Stable, using a foal-sharing agreement. On March 30, 1970, at 12:10 a.m. at the Meadow Stud in Caroline County, Virginia, Somethingroyal foaled a bright-red chestnut colt with three white socks and a star with a narrow stripe. Secretariat was born.

The foal stood when he was 45 minutes old and started nursing another 30 minutes later. Howard Gentry, the manager of Meadow Stud, was at the birth and would later say, "He was a very well-made foal. He was as perfect a foal that I ever delivered." He soon started distinguishing himself from the other foals. "He was always the leader in the crowd," said Gentry's nephew, Robert, who also worked at the farm. "To us, he was 'Big Red', and he had a personality. He was a clown and was always cutting up, always into some devilment."

Secretariat grew into a massive, powerful horse said to resemble his sire's broodmare sire, Discovery. He stood 16.2 hands (66 inches, 168 cm) when fully grown. His heart girth was so large that he required a custom-made girth, and he was noted for his large, powerful, well-muscled hindquarters. An Australian trainer described his appearance by saying, "He is incredible, an absolutely perfect horse. I never saw anything like him."

Seth Hancock of Claiborne Farm once said, "You want to know who Secretariat is in human terms? Just imagine the greatest athlete in the world. The greatest. Now make him six-foot-three, the perfect height. Make him real intelligent and kind. And on top of that, make him the best-lookin' guy ever to come down the pike. He was all those things as a horse."

When Penny Chenery's father passed away, rather than lose her farm to taxes, she syndicated Secretariat for a record-breaking $6.08 million, but kept 3 shares for herself along with control of his racing career until the end of the season.

While training for the Preakness Stakes, his stride was measured as 24 feet, 11 inches. His weight before the Gotham Stakes in April 1973 was 1,155 pounds (524 kg). After completing the grueling Triple Crown, his weight on June 15 had dropped only 24 pounds, to 1,131 pounds (513 kg). Secretariat was known for his appetite - during his three-year-old campaign, he ate 15 quarts of oats a day!

Secretariat raced in Meadow Stables' blue-and-white-checkered colors. He never raced in track bandages, but typically wore a blinker hood, mostly to help him focus. He gained a reputation as a kind horse, likeable and unruffled among crowds.

Groom Eddie Sweat was another important member of the Secretariat team, responsible for his day to day care. The book, The Horse God Built, focuses on Sweat's relationship with Secretariat. Sweat once said, "Only way that horses win is if you sit there and spend time with 'em. Show 'em that you're tryin' to help 'em. Love 'em. Talk to 'em. Get to know 'em. That's what you gotta do. You love 'em and they'll love you, too."

As a two year old, Secretariat won the Eclipse Award for American Champion Two-Year-Old Male Horse and, in a rare occurrence, two two-year-olds topped the balloting for 1972 American Horse of the Year honors, with Secretariat edging out the undefeated filly, La Prevoyante.

The 1973 Kentucky Derby on May 5 attracted a crowd of 134,476 to Churchill Downs, then the largest crowd in North American racing history. On his way to a still-standing track record of 1:59 2/5, Secretariat defeated Sham, and ran each quarter-mile segment faster than the one before it. The successive quarter-mile times were :25 1/5, :24, :23 4/5, :23 2/5, and :23. This means he was still accelerating as of the final quarter-mile of the race. No other horse had ever won the Derby in less than 2 minutes, and it would not be accomplished again until Monarchos in 2001.

Sham was fast, a beautiful horse. He would have had the Triple Crown in another year. And it just didn't seem like there could be anything faster than that. Everyone in the Derby crowd was watching him. It seemed like it was over, more or less. And all of a sudden there was this, like, just a disruption in the corner of your eye, in your peripheral vision. And then before you could make out what it was, here Secretariat came. And then Secretariat had passed Sham. No one had ever seen anything run like that - a lot of the old guys said the same thing. It was like he was some other animal out there.

In the 1973 Preakness Stakes on May 19, Secretariat broke from the gate last, but then made a huge, last-to-first move on the first turn. Once again Secretariat beat Sham who again finished second with Our Native in third, a further eight lengths back. It was the first time in history that the top three finishers in the two races were the same; the distance between each of the horses was also the same. After a forensic review. Secretariat's winning time was adjusted from 1:54 2/5 to 1:53, establishing a new Preakness Stakes record.

As Secretariat prepared for the Belmont Stakes, he appeared on the covers of three national magazines: Time, Newsweek, and Sports Illustrated. He had become a national celebrity. William Nack would write: "Secretariat suddenly transcended horse racing and became a cultural phenomenon, a sort of undeclared national holiday from the tortures of Watergate and the Vietnam War."

Only four horses ran against Secretariat for the June 9, 1973 Belmont Stakes, including Sham and three other horses thought to have little chance. Secretariat was expected to win and went off as a 1-10 favorite. Neck and neck at the outset, Sham and Secretariat ran the first quarter in a quick :23 3/5 and the next quarter in a swift :22 3/5, completing the fastest opening half mile in the history of the race and opening ten lengths on the rest of the field. Sham began to tire, ultimately finishing last. Secretariat continued the fast pace and opened up a larger and larger margin on the field, winning by an unprecedented 31 lengths, breaking the margin-of-victory record set by Triple Crown winner Count Fleet in 1943 of 25 lengths. Secretariat had run the fastest 1 1/2 miles on dirt in history, 2:24 flat, breaking the stakes record by more than two seconds! Secretariat's record still stands today. When it was clear that Secretariat would win, the crowd cheering reached a crescendo that reportedly made the grandstand shake.

Altogether, 'Big Red' won 16 of his 21 career races (having been ill during several of his races), and took three seconds and one third, and total earnings of $1,316,808, equivalent to $7,019,357 in 2015.

For 1973, Secretariat was again named Horse of the Year, and won Eclipse Awards as the American Champion Three-Year-Old Male Horse and the American Champion Male Turf Horse.

Due to the terms of the syndication agreement, Secretariat retired from horse racing after the 1973 season to stand at stud at Claiborne Farm. Ultimately, Secretariat sired 341 winners (51.4%) and 54 stakes winners (8.1%) from 663 named foals according to Jockey Club records. There has been some criticism of Secretariat as a stallion, due in part to his inability to produce male offspring of his same caliber. He did not leave a leading sire son behind. However, his legacy is assured through the quality of his daughters, several of whom were excellent racers and even more of whom were excellent broodmares. Overall, Secretariat's daughters produced 24 Grade 1 winners.

More on the life and times of Secretariat:

Secretariat - The 2010 Disney film about the life of Secretariat and owner Penny Chenery

Penny & Red - the documentary film on the life of the First Lady of Horse Racing, Penny Chenery, the tough, earthy owner of the legendary Secretariat

The Horse God Built - a moving portrait of the powerful bond between horse and human, Secretariat's groom Eddie Sweat