Ranavalona I ruled Madagascar through an era of fierce isolationism, determined to keep European powers and their missionaries at arm's length while still acquiring the tools of a modern state. Laborde, one of the few foreigners she favored, became the instrument of that ambition. Under contract with the queen, he chose Mantasoa for its access to water, wood, and iron ore, and there he assembled an astonishing range of production under one program. The works turned out cannons, rifles, bullets, and swords alongside bricks, tiles, pottery, glass, porcelain, silk, soap, candles, cement, sugar, rum, even sulphuric acid and lightning conductors. It was an attempt to compress an industrial revolution into a single Malagasy valley.

The complex did not rise on wages and willing hands. By many accounts Laborde marshaled some twenty thousand forced laborers to construct it, conscripted Malagasy workers who cut the timber, raised the dams, and built the furnaces that made the queen's vision real. Around twelve hundred workmen ran the operation once it was going. The scale of the achievement and the scale of the coercion are inseparable: this was one of the most ambitious industrial projects in 19th-century Africa, and it was made possible by compelled labor under a system that gave those workers no choice. Remembering Mantasoa means holding both facts at once, the ingenuity and the human cost beneath it.

Mantasoa today is defined as much by water as by industry. Lake Mantasoa, formed behind a dam, covers more than twenty square kilometers and fills nearly a fifth of the municipality, its shores planted with eucalyptus and pine where only a sliver of the original highland forest survives. The old factory premises now house schools, including the Lycee Jean Laborde, so that the site Laborde built still trains young people more than a century and a half later. The Peace Corps runs its Madagascar training center here as well, drawn by the same cool lakeside calm that makes Mantasoa a weekend escape from the capital.

Strip away the history and Mantasoa is, day to day, a community of farmers. Almost the entire population works the land, growing rice in the valleys and beans, cassava, and sweet potatoes on the hillsides the Malagasy call tanety. Sixty villages spread across eleven fokontany make up the commune, fed by the Ikopa River and its tributary the Varahina. The contrast is what gives the place its texture: a landscape of rice paddies and grazing livestock wrapped around the rusting evidence of a queen's failed bid to industrialize her island on her own terms.

Water was the engine of Laborde's works, and it still shapes the place. To drive his machinery he dammed the local rivers. The large lake that now defines the commune, however, was created by a later concrete dam built by French colonial engineers in 1937 and 1938 — long after Laborde's exile — which flooded the valley to generate hydroelectric power. What once ran waterwheels for a foundry in Laborde's day became, a century later, a 20-square-kilometer reservoir that draws weekend visitors from the capital for sailing, swimming, and quiet. It is a fitting second act for a site built around the control of water: the valley Laborde harnessed to arm a 19th-century queen was later dammed again by her colonizers, and now offers nothing more demanding than an afternoon on the shore, with the ruins of the old factory standing a short walk inland.