The French Equestrian Team proved its superiority over the U.S. team during this week's Washington International Horse Show at Capital Centre with a victory in the Nations' Cup. The U.S. team had not lost this event in eight years, but the defeat was consistent with its performance in this week's international jumper classes.

Each of the four-member teams completed two rounds in the 12-fence event, with each team keeping its best three performances. The team with the fewest total faults was the winner.

France, which has won three of four jumper classes since Sunday, completed two clear rounds in its second attempt at the course to win with 17 points. Phillipe Rozier and Hubert Bourdy scored faultless rounds in their second attempts to guarantee the French victory.

The United States scored 29 points after trailing by only .25 points after the first round. Sixteen fault points in the second round put the Americans out of contention.

With the victory, France secured the Gucci Cup, awarded to the top scoring team in the 18 Nations' Cup competitions.

The jumper events are the most exciting classes at almost any horse show. In the jumpoff rounds, those entries that faultlessly finish the 13-fence course race against the clock over a five-fence course to determine a winner.

The times are usually close, but rarely as close as those in the Washington International Horse Show's $7,500 Range Rover Open Jumper competition yesterday at Capital Centre.

Chris Kappler and Concorde were leading with a time of 34.33 seconds when the final horse and rider entered the ring.

After clearing the final fence, Mario Deslauriers and Box Car Willie moved so quickly that Deslauriers fell off the horse after crossing the finish line. The 22-year-old Canadian was uninjured and ended up tied with Kappler and Concorde.

The two winners finished ahead of Katie Monahan Prudent and Special Envoy. Monahan Prudent and Special Envoy finished second in a pair of international jumper events that were held earlier this week.

Monahan Prudent, 1986 rider of the year and the leader in the national rider competition with 14 points, finished atop the 9-year-old gelding in 35:52.

Lisa Tarnapol of New York, riding Revlon Adam, was fourth in 35:59.