On the July 4th weekend, William Fannon packed up 18 horses, two grooms, six saddles and 20 mallets and then drove 60 miles from his farm in Castletown, Va., to West Potomac Park -- all for two hours of polo. "You have to be dedicated to the game," he said.

Fannon, an owner of Fannon Oil Companies, is much like other area polo players -- he's addicted to the fast-paced sport that requires a lot of time, money, skill and guts. After all, the game involves riding on 2,000-pound horses that kick, turn, jump and run 40 miles per hour.

The thundering herd of tangled hooves, arms and mallets can be seen most Sunday afternoons from May to October at West Potomac Park, stirring up a dust bowl in the shadow of the Washington Monument.

While the polo games are one of Washington's best kept secrets, regular crowds of 400 to 1,000 fans surround the field with blankets and folding chairs to watch the sport that gives new meaning to the term hot to trot, as the horses and riders race by with veins pounding and nostrils flaring.

Polo, the sport of kings, has been a tradition in Washington since 1968, when the first game was sponsored by the National Capital Polo Association. Since then, more than 2,000 games have been played between the Washington Monument and the Tidal Basin on a behemoth field that is 300 yards long and 160 yards wide -- the equivalent of nearly nine football fields.

"Gen. George Patton used to play on the same field years ago when the Army kept horses at Fort Myer," said Jack Sted, executive director of the National Capital Polo Association, also called the Lincoln Mall Polo Club.

In the Washington area, there are about 180 polo players, including 10 women.

"It's a very eclectic game," said Tom Hulfish, who serves as a game umpire. West Potomac Park is the only place in the District where polo is played. Hulfish's son Charles serves as the game announcer.

"You use the rules to your advantage and it becomes very cerebral. You have to think about eight seconds ahead of yourself or you can really get hurt," the elder Hulfish explained. "Polo is not a sport. It's a terminal disease."

Actually, it's a little like hockey played on horseback, the object being to bash a 3 1/2-inch plastic ball through goal posts eight yards apart, at either end of the field.

The game, played by four-member teams, is divided into six "chukkers" lasting 7 1/2-minutes each, with five-minute breaks between chukkers to give players time to change horses. There is also a 15-minute halftime break. Each horse can play two chukkers if given plenty of time to rest up.

The sport attracts all kinds of people, Hulfish said.

"We have people who are blacksmiths that play, we have people who drive a truck and play, and we have people who are millionaires who play," Hulfish said. "It depends on how dedicated you are."

On any given Sunday afternoon don't expect to see too many truck drivers playing polo in Washington, however. It simply isn't a cheap sport. Eighty-five percent of polo horses are thoroughbreds, which cost anywhere from $5,000 to $15,000 apiece. If you have to settle for a quarter horse, expect to pay $2,000 to $2,500 per horse.

"By the time you buy a truck and horse trailer, you're talking $10,000," said Fannon, who owns the Rappahannock Polo Club. There also are polo clubs in Potomac, Middleburg and Charlottesville.

Sted said the association has spent more than $80,000 over the last 10 years to maintain the field, which is on National Park Service land. "We spend anywhere from $6,000 to $8,000 a year on the field and we take a break in August to get it back in shape for the fall."

Other costs include a horse groom for $100 to $200 a week, "and feed costs $30 a week per horse . . . most local club dues run $1,500 to $2,000 and big-time club dues average $5,000 a year," Fannon said. Then there are the polo mallets, which each cost $60, "and you run through about 20 mallets a season." Saddles and bridles are extra.

For spectators it is an experience unlike any other in Washington. To see riders race by, dangling one-handed from a panting mass of frothing muscles, one may as well be a character in a James Bond novel sipping Tanqueray gin at the Hong Kong Polo Club. It's a gentleman's sport with an elegant history.

"If you like polo, it's better to watch it at West Potomac Park than in Potomac Maryland ," said Cherri Corbin, of Falls Church, at a recent game. "In Potomac it's a lot more commercial . . . they have the bar and people really dress for games. It's more of a social event and it's not easy to watch the game."

"I love watching the players balancing on the horses and the physical contact," said Susan Medjo of Northwest, as she peered anxiously through binoculars at a recent game. "I think it takes a great deal of talent to ride those horses."

Polo players will tell you the horses have a mind of their own, can be temperamental, and, as one player so delicately put it, "they're dumb." It takes at least two years of daily training to prepare a horse for polo, and then they must continue to be exercised daily to stay in top physical shape.

Holly Hamilton knows horses. "Look at him, he's loving this," she said washing down the sweaty face of a gray horse that had just come off the field. It was 97 degrees that afternoon, and the horse was glistening with sweat.

Hamilton, who grooms for brothers Tom and Allen Nash, said it takes her seven minutes to prepare a horse for play, including wrapping each leg, putting on the tack, bandaging cuts and applying bug spray.

The game can be grueling. A few years ago, while playing polo in Argentina, Fannon was thrown to the ground when his horse lost its footing. Fannon broke his shoulder, an arm and several fingers, and cracked four ribs and a hip. "You learn how to fall," he said. "I ride every day and if you don't stay in shape you're going to get banged up."

Vincey Rizzo, who travels from his 50-acre farm in West Virginia to play in Washington, said polo is a tradition in his family. "My father played, my cousin plays and my uncle plays. It's a family sport."

"It's the competitiveness of it," said player Phillip Staples.

"There's only two reasons you give up polo," explained Hulfish, who is in his early 50s and has been playing polo for 17 years. "Either you die or you go broke."