An Epidemiological Barrier
The Great Plague of Marseille began with a single ship. On May 25, 1720, the merchant vessel Grand-Saint-Antoine arrived in Marseille's harbor from the Levant. Although the ship had experienced several deaths at sea, its valuable cargo of silk and cotton bales was eagerly awaited for an annual trade fair. The ship's owner, who was also the deputy mayor of Marseille, successfully pressured health officials to lift the quarantine prematurely. This decision allowed rats carrying fleas infected with the bacterium Yersinia pestis to come ashore.
Within days, the disease began to spread through the city. Hospitals were quickly overwhelmed, and at the outbreak's peak, nearly 1,000 people died per day. The city's public health systems collapsed, leaving thousands of bodies in the streets. To stop the plague from consuming the rest of France, the Parliament of Aix passed an act imposing the death penalty for anyone communicating between Marseille and the rest of Provence. To enforce this cordon sanitaire, authorities ordered the construction of a physical barrier: the Mur de la Peste, or Plague Wall. The wall was intended to seal off the infected region and protect the neighboring papal territory of Comtat Venaissin.
Construction and Efficacy
Construction of the Plague Wall began in 1721. The dry-stone wall stretched for 27 kilometers across the countryside of the Vaucluse mountains. It stood approximately two meters high and was built without mortar. Along its length, stone guard huts, or guérites, were constructed to house soldiers with orders to shoot anyone attempting to cross.
Despite this extreme measure, the plague still managed to breach the quarantine. Thousands of people had already fled the city before the wall was completed, carrying the disease with them into the countryside. The plague eventually appeared in towns north of the wall, including Apt and Avignon. The epidemic lasted for two years before finally ending in 1722.
The wall was only partially successful. The final death toll was catastrophic: approximately 50,000 people died in Marseille, which was about half of the city's population. Another 50,000 perished in the surrounding northern provinces. While the total of 100,000 deaths was immense, the wall is credited with slowing the plague's spread and preventing a nationwide pandemic that could have killed millions.