Dempsey was introduced as a 70th minute substitute in place of Bolton's Sam Sheridan, and he is the first player from the club to be capped by his country following the Youths' entry into League of Ireland as a senior club last season.
Former Wexford Youths underage star and Republic of Ireland International striker Kevin Doyle, has been capped at numerous levels for his country, but Dempsey is the first senior Wexford Youths FC player to represent his country.
"I was nervous at the first but then after hearing the national anthem and after the warm up I was pumped up and ready to play," the 18-year-old Wexford Town native said.
"It was a great honour and it was brilliant to play against the French. Some of their players were awesome and a few of them are strongly linked with moves to top Premiership Clubs.
Wexford Youths FC manager Mick Wallace has been careful with Dempsey and has used him sparingly for the senior side, as Dempsey is an integral part of the under-18 side who are aiming to retain their All-Ireland Youth crown this year.
"I've been concentrating on the under-18's a lot lately but hopefully I can start to feature a bit more for the senior side as well," Dempsey added.
Wallace brothers make Youths debut
Gareth and Conor have been an integral part of Mick Wallace's successful under-16 and under-18 Wexford Youths' squads and Gareth, who only turned 16 this month and has been capped by Ireland at under-15 and under-16 level, is the youngest player ever to appear for the club's senior side.
Along with older brother Conor, 17, the Wallace brothers, who are not related to club owner and manager Mick, were among five under-18 players that appeared for the hosts in their memorable 1-0 victory over Premier Division side Cobh, thanks to a Liam O'Loughlin strike in extra-time.
The first set of brothers to appear for Wexford Youths FC in the League of Ireland were the Russell brothers, current club captain Anthony and goalkeeper Jason, who lined out together regularly last season and have started all of this season's league games.
The Rossiter brothers, defender Anthony and midfielder Paul, also lined out for Mick Wallace's senior side last season.

