- A meiboom ("May tree"), traditionally called the tree of Saint Lawrence (arbre Saint-Laurent), is placed each year at the corner of rue des Sables and rue du Marais in a tradition whose origins date to 1311 in celebrating a victory of Brussels over Leuven. Legend holds that Duke John III (r. 1312-1355) granted the guildsmen of Saint Lawrence the favor of raising a tree in perpetuity in honor of the members having gone to the rescue of a wedding party celebrating at the Caltenhuys, an inn on rue du Marais, who were attacked by a band of men from the Guild of Saint Peter (Peetermannen) from Leuven. The event took place on 9 August, the eve of the feast of Saint Lawrence, and the annual commemoration mandates that the tree be planted before the 18th hour (before vespers) on pain of misfortune. It was believed planting a tree marked a defiant gesture toward the men of Leuven, who viewed it as a humiliating insult. The tree is paraded from the place Sainte-Catherine via the Grand' Place by residents in medieval costume joined by giant characters (including Jantje, Mieke, Jefke, and Rooste). The city's red and green flag is affixed to the tree's top by nimble climbers. A bush or simple plant is sometimes used to symbolize the tree.Every year men from Leuven traditionally send emissaries to try to prevent the tree planting but residents of Brussels, ever vigilant, have stymied the effort. The only exception occurred in 1939 when a fight erupted near the church of Sainte-Marie and, taking advantage of the diversion, interlopers from Leuven loaded the tree onto a truck and returned home. A nearby shrub was used instead and the onset of World War II prevented the Brusselers from securing revenge.
Historical Dictionary of Brussels. Paul F. State.