In February 1840, Captain Lelievre and 122 soldiers from the 10th Company of the Battalion of Africa -- a French penal military unit -- occupied a small fort in the town of Mazagran, near the port city of Mostaganem. Their supplies were modest: a single four-pound gun, one barrel of gunpowder, and between 30,000 and 40,000 cartridges. The French conquest of Algeria, which had begun with the invasion of Algiers in 1830, had entered a new phase after French troops deliberately violated the 1837 Treaty of Tafna, prompting Abd al-Qadir to renew armed resistance. The garrison at Mazagran was a small piece in a much larger, and much uglier, colonial war.

Algerian resistance forces under Ben Khami, one of Abd al-Qadir's lieutenants, surrounded the fort with a force the French initially claimed numbered ten to twenty thousand -- though later analysis suggested the actual strength was between five and six hundred. Khami's troops, primarily cavalry, had two eight-pound guns but could not use them effectively against the fortification. For two days the garrison repulsed repeated attacks. During a lull, Lelievre inventoried his remaining supplies and found only 10,000 rounds left. He proposed to his men that they fight until the ammunition ran out, then blow up the gunpowder barrel as a final act. His soldiers agreed enthusiastically. The fighting resumed for two more days until a relief column from Mostaganem arrived and the Algerian forces withdrew.

Paris went wild. Newspapers devoted columns to the siege. A replica of the Mazagran fort was built on the Champs-Elysees, and commemorative merchandise flooded the market. Lelievre and six of his soldiers received the Legion d'honneur. The French government issued a special medal. The battle became the official anniversary celebration of the Battalions of Light Infantry of Africa. An empire hungry for validation had found its story: a handful of brave Frenchmen holding out against impossible odds in the wilds of North Africa. It was exactly the narrative colonial conquest required.

In 1842, the London Morning Chronicle -- irritated by French mockery of Britain's disastrous withdrawal from Afghanistan -- published an accusation that the entire affair was a hoax and challenged the French government to prove otherwise. Paris did not respond. A British military correspondent later wrote that he had met an unnamed French officer who confirmed that something resembling the battle had occurred, but that its scale and drama had been enormously exaggerated. The officer reported that Lelievre himself was embarrassed by the attention and honours heaped upon him, and eventually requested a transfer out of his regiment. A subsequent French analysis quietly revised the Arab strength down from thousands to a few hundred. The legend, however, had already done its work.