While he was serving his year of military duty at the end of World War I, Leemans's regimental commander asked him to compose a march; it was begun but never finished. Near the end of World War II he was having dinner with a group of paratroopers and was again asked to compose a march. As the group commander, Maj. Timmerman, drove him home that night, the march theme came to mind, and he wrote out all of the parts after reaching home.

The trio of the march originated from a march written for an N.I.R. radio contest. After only winning the consolation prize, the march was abandoned and is known with the competition designation V. A quiet, unaggressive essay in the easy-paced European style, it is set in the form of a “patrol”; the music marches on from the distance, plays, and passes.

Friends told him later that they had heard the march at a circus in France, a wedding in India, and a military music pageant in the United States. The arrangement most often heard in the United States was made by Charles Wiley at the request of his Lamar University (Texas) Band students in 1975.
https://www.windrep.org/March_of_the_Belgian_Parachutists