He watched the horse walk; a gait like a leopard’s signaled a champion runner. This yearling didn’t have it, but Sheik Mohammed followed through on his brother’s wishes and bid anyway. His main competition was a representative of the Coolmore group. The two traded bids up to $3.4 million. When his rival offered $3.5 million—more than double what any yearling had ever gone for—Sheik Mohammed pulled out. The horse turned out to be a dud, racing only five times and never going to stud. Sheik Mohammed, however, didn’t leave the auction empty-handed; he picked up a horse for his brother for $3.3 million that Sheik Maktoum named Shareef Dancer. The yearling went on to be syndicated—the equivalent of an initial public offering for a horse—for a then- unprecedented $40 million.

“The one that I discarded?” says Sheik Mohammed, pretending to struggle to remember the horse’s name. “Was it Ballydoyle or something?” he asks Crisford. Then the sheik bursts out laughing and gives Crisford a high five. Ballydoyle is both the name of the horse and the racing arm of Coolmore.

UNLIKE IN OTHER sports, where hated rivals battle on the playing field, the great Arab-Irish wars are waged almost entirely in the auction ring. It’s here that John Magnier builds his business. From the start, Coolmore was based on the idea that there was money to be made in buying the top yearlings with the best pedigrees, racing them a few times to build credentials, then retiring them to stud.

When Magnier came up with this plan, in the mid-1970s, he was a nobody, a small family stud operator in Ireland who had dropped out of school as a teenager to take over the farm after his father died. He went into business with his future father-in-law, who was a world-famous horse trainer, and with Robert Sangster, an English gambling heir. Naming their enterprise Coolmore, the three men began flying to auctions in Kentucky and buying the best young horses descended from Northern Dancer.

What Magnier did next forever changed the industry. At the time, conventional wisdom held that a stallion could breed with 40 to 45 mares a year; anything more than that would pollute an already tiny gene pool with too many foals from too few fathers. Magnier believed otherwise; his family had always mated steeplechase stallions with hundreds of mares, without problem. At Coolmore, he turned racing stallions into machines, mating them in some cases with 200 mares a year and shuttling them between the group’s operations in the Northern and Southern Hemispheres to take advantage of the fact that a mare’s short breeding window—which always begins in the spring—occurs six months later below the equator. The business got a lift from the Irish tax code, which exempts stallion earnings.

When Sheik Mohammed decided that he, too, favored the Northern Dancer line, the fight between the Irish and the Arabs was on. By the late 1980s, the Maktoums had clearly gained the upper hand at the sales and on the track. Sangster largely gave up funding purchases, telling a friend, “They have a country behind them, and I have a small business.”

In the covering sheds, however, Magnier still controlled the best of the Northern Dancer bloodline, and until 2005, even counted the Maktoums as clients. Nearly 10 percent of Godolphin’s racers and 19 percent of Sheik Mohammed’s stallions were sired by Coolmore horses.

Eventually, Magnier used the profits from his stud operations to invest in businesses ranging from sausage casings to nursing homes, and for several years, he held a significant stake in Manchester United. He co-owns the Sandy Lane resort in Barbados, home to the $4,000-a-round Green Monkey golf course and site of Tiger Woods’ 2004 wedding. Britain’s Sunday Times two years ago estimated Magnier’s net worth at $1 billion, designating him the eighth-richest person in Ireland. Despite repeated requests, Magnier would not consent to an interview. “We just run a farm,” says a spokesperson.