From Pagan rite to Catholic procession to sociopolitical declaration, La Saint-Jean-Baptiste Day -- called La Fête Nationale in more recent times or simply "La Saint-Jean" -- is a statutory holiday in Quebec on June 24, with origins dating back over 2000 years.
Summer Solstice Meets Clovis
Much in the same way the celebration of Jesus Christ's birth was moved near the winter solstice, Clovis -- the 5th century Frankish king who ruled over what is now France and converted to Catholicism at his wife's insistence -- decided that St. John the Baptist's birth would be honored on June 24, within days of the summer solstice, eventually and effectively overshadowing the Pagan festival. Clovis' Saint-Jean-Baptiste Day also borrowed the bonfire lighting, originally a solstice tradition, and cleverly paralleled the solstice's job, the announcing of summer's light, with John the Baptist's role as per the Bible, that of heralding the arrival of the Messiah.
New France Celebrates Saint-Jean-Baptiste
The first accounts of Saint-Jean-Baptiste Day celebrations among colonists in New France come from the Jesuits and go back to 1636 on the shores of the St. Lawrence River. By 1646, cannons, muskets as well as bonfires were reportedly lit, heralding the festivities.
Duvernay and the Société
On June 24, 1834, Ludger Duvernay, owner and editor of La Minerve, an important Montreal newspaper supporting the views of the Patriotes party, created the Société Saint-Jean-Baptiste, but there's no documentation to prove it was an association until 1843. Created to stimulate a stronger defense of the French language and culture, the first "official" Saint-Jean-Baptiste banquet in Montreal was celebrated with a Catholic Mass and procession, taking place in a prominent lawyer's private gardens, today the location of the Windsor Station. About 60 influential Montrealers attended the banquet, Catholic Mass and procession, including:
Official website of La Fête Nationale du Québec (In French).
The Canadian Encyclopedia on Saint-Jean-Baptiste Celebrations.
Golden Gate Geneology Forum
Stanley, A. (1990, June 24). Moody and Torn, Quebecers Explore a Future Quite Apart. The New York Times.
Controversial 1969 Saint-Jean-Baptiste Parade Video Clip(In French).