"The Eagle of Flanders" joined the Belgian Air Service on 26 January 1915 and was posted to 1ère Escadrille de Chasse on 8 April 1917. Sharing an unconfirmed victory with another pilot on 18 October 1917, de Meulemeester is believed to have downed Xavier Dannhuber's Albatros near Tervaete. Flying the Nieuport 17, de Meulemeester was credited with six victories before his unit was re-equipped with the Hanriot HD.1. In the spring of 1918, he was joined 9me, scoring four more victories by the end of the war. During 511 sorties, de Meulemeester engaged the enemy in aerial combat 185 times, was wounded in action twice and was attacked by British D.H.4s on two occasions. In 1919, de Meulemeester left the army, gave up flying and went to work in his family's brewery business.