[2] Brillant volunteered for service with the 89th (Temiscouata and Rimouski) Regiment (from 1920 the Fusiliers du St-Laurent) and held the rank of lieutenant.

After about six months’ training in Valcartier, he embarked for England with the 189th on 27 September 1916; on disembarking at Liverpool on 6 October, he was assigned to the 69th Infantry Battalion.

[2] During the night of 27/28 May 1918, in the vicinity of Boiry-Becquerelle, Brillant was called to lead a group of volunteers to help silence an outpost defended by about 50 men.

For most conspicuous bravery and outstanding devotion to duty when in charge of a company which he led in attack during two days with absolute fearlessness and extraordinary ability and initiative, the extent of the advance being twelve miles.

Lt. Brillant's wonderful example throughout the day inspired his men with an enthusiasm and dash which largely contributed towards the success of the operations.Brillant is buried at Villers-Bretonneux Military Cemetery, Fouilloy, France located 15 km (9 miles) east of Amiens.

GOOD BLOOD DOES NOT LIE (a French expression meaning that he bore the positive traits of his ancestors)[5] His medals are held at the Royal 22e Regiment Museum in Quebec City.