Colbert is mercantilism in office. As controller-general of finances to Louis XIV from 1665, he had something no theorist did — an absolute monarchy, a large population, and thirty years — and he used them to attempt the systematic construction of a national economy by administrative means.
The program was comprehensive. Tariffs raised repeatedly to shut out Dutch and English manufactures; royal manufactories founded and subsidised in glass, tapestry, lace and armaments; foreign artisans recruited and emigration of skilled workers made a crime; guild regulation extended and standardised so that French goods would carry a reputation for quality; roads and canals built, the Canal du Midi among them; a navy and a merchant marine created almost from nothing; chartered companies granted monopolies over colonial trade, with the colonies forbidden to manufacture for themselves.
The theory behind it was frankly zero-sum. Colbert held that the volume of European trade was fixed and that a state enriched itself by capturing a larger share, which made commerce a continuation of war — a view that helped produce several actual wars, including the Dutch War of 1672.
The results were mixed in his lifetime and consequential long after. He built real industrial capacity and a fiscal machine that outlived him, at the cost of a peasantry taxed to fund it and an economy so regulated that the Physiocrats a century later took French agriculture's stagnation as their founding grievance. "Colbertism" remains the name for state-directed industrial development, and French economic policy has returned to it repeatedly.