In a race that became a battle of jockeys as much as horses, the Washington, D.C. International was captured by one of America's most-maligned riders.

Jean Cruguet drove the colt Mac Diarmida to a head victory at Laurel yesterday, leading a one-two-three American sweep of the 27th International. He outrode Jeffrey Fell on runner-up Tiller, and Sandy Hawley on fourth-place finisher Trillion, either of whom might have won had they created better luck for themselves.

The victory was Mac Diarmida's 12th in 13 starts on the grass this season, but he had accomplished his previous triumps at the expense of relatively weak opposition. Yesterday he and Cruguet had to work hard for the entire mile and one half.

A crowd of 20,520 watched, betting $2,061,503 for the day.

Mac Diarmida broke next to last in the eight-horse field, but Cruguet quickly realized that leader Noble Dancer was setting a slow pace. So while the field was covering the first half-mile in a tortoiselike 50 seconds, Cruguet urged his mount to the middle of the pack, within easy striking distance.

Hawley recognized the slow pace, too, and sent the favored French filly Trillion up outside the leader. He kept her there around every turn, losing valuable ground, a mistake he would acknowledge later. "It probably would have been better to put her on the lead and let them catch her."

Tiller and Waya were trailing the field through the first mile. While Waya always runs this way, Tiller is a more tractable animal, and Fell was spotting too much ground to the horses in front of him.

The field bunched as it reached the final turn, the place where turf races are usually won by the jockey who can save ground and avoid trouble. New York's legion of Cruguethaters would not have wanted their money on Mac Diarmida at this moment, for the colt appeared to have a wall of horses in front of him, just as he was ready to make his run.

But Cruguet wasn't worried. One of the animals in front of him was Trillion, and he said. "She's a big mare and I'd seen her come out at the first turn. When we came into the stretch, she came out again - just enough for me to go through."

Cruguet gunned Mac Diarmida past the fading leader, Noble Dancer, just as the field straightened out into the stretch. Meanwhile Trillion was losing ground on a turn for the third time, and Tiller was going even wider, circling the entire field in the middle of the track.

Mac Diarmida opened a brief clear advantage, but when Tiller straightened out into the stretch and regained momentum, he closed ground with every stride. Fell, however, was asking his mount to do the impossible - close so much ground against horses who were still strong after running a slow early pace. Although Tiller covered the last quarter-mile in 23 seconds - a virtual superhorse performance - his rally fell short by a head.

Mac Diarmida covered the distance in 2:27, and paid $11.60, $6.20 and $3.40. Tiller returned $6.60 and $3.60. Waya, who finished three lengths farther back, paid $2.80. The exacta wa worth $46.80.

In New York's Off-Track Betting, Mac Diarmida paid $8.80.

The victory was worth $120,000 to Mac Diamida's owner. Dr. Jerome Torsney, a New Jersey allergist who bough the colt as a yearling and named him after one of the leaders of the Easter 1916 rebellion in Ireland. ("He was a patriot, or a revolutionary, depending on your point of view, Torsney said.)

The triumph also boosted Mac Diarmida's credentials for the Eclipse Award as the best turf horse of the year. "In my opinion," trainer Scotty Schulhofer said, "she should win it. What else can you ask a horse to do?"

The International probably meant as much to Mac Diarmida's jockey as it did to his owner and trainer. Earlier this fall Cruguet suffered the greatest disappointment of his career when he was fired as the jockey of Seattle Slew. Mac Diarmida has not only soothed his feelings of frustration, but also helped Cruguet demonstrate how well he can sometimes ride.