After making the podium on three other occasions at the Summer Fort Classic, Mannix broke through with an impressive win.
show jumping
The Frenchman topped the field of 35 at the Hubside Jumping de Valence in front of grandstands full of enthusiastic crowds.
As the border gradually reopens to non-citizens, it sees the welcome return of international competition to Thunderbird Show Park.
The US team member claimed first, third, fourth and fifth places in the $5,000 Horseware Ireland Welcome Stake at TIEC.
The German edged Swedish rider Peder Fredricson who has been riding the Olympic momentum, placing second aboard H&M Christian K.
Fresh off his Olympic gold and silver medals, the Swedish rider narrowly beat British superstar John Whitaker for top spot.
Highlights from the Summer Series include Sybil Moylan (daughter of Canadian rider Gavin) and Churchill being named Leadline champions.
The final grand prix of the Ocala NSBA Summer Series saw a win for the US rider; Canadian Angela Covert was 9th riding Hollywood De Rase Z.
The American rider has enjoyed great success at World Equestrian Center-Ocala, and this marked his eighth Grand Prix victory.
The top 30 tackled Santiago Valera’s large and demanding course with Deslauriers picking up 13 penalties during his trip.