Although the French emperor Napoleon Bonaparte died nearly two centuries ago, his mark on Louisiana remains clear. His Napoleonic code continues to be the basis of state law. Napoleonville, the parish seat of Assumption Parish, is named in his honor. He is also memorialized by the Napoleon House bar and restaurant in New Orleans.

But Napoleon’s chief legacy to Louisiana is Louisiana itself. In 1803, he sold the territory that includes Louisiana to the United States, advancing what is arguably history’s biggest real estate deal. That grand bargain, which paved the way for a young America to become a world superpower, is getting some fresh attention, thanks to a new biography of Napoleon by Andrew Roberts.

Nothing that Napoleon did was without controversy, and the Louisiana Purchase is a prime example of how he operated. Napoleon had told Spain that he wouldn’t sell Louisiana to a third party, but like many a politician then and now, he wasn’t about to let an inconvenient promise get in the way of doing what he wanted.

“President Thomas Jefferson signed the Louisiana Purchase, doubling the United States at the stroke of his pen,” Roberts tells readers. “The Americans paid France 80 million francs for 875,000 square miles of territory that today comprises all or some of thirteen states from the Gulf of Mexico across the Midwest right up to the Canadian border, at a cost of less than four cents an acre.”

It was a great deal for the United States, but Napoleon thought it was a good deal for him, too. Defending that much territory from the United States would be an expensive distraction for him, so why not sell it outright to a potential rival and at least get some quick cash? In strengthening the United States, or so Napoleon figured, he could also create a foil for his principal adversary, Great Britain.

After inking the deal with Jefferson, Napoleon predicted, “I have just given to England a maritime rival that sooner or later will humble her pride.” As Roberts points out, Napoleon was right: “Within a decade, the United States was at war with Britain rather than with France, and the War of 1812 was to draw off British forces that were still fighting in February 1815, which might otherwise have been present at Waterloo.”

Even so, Napoleon lost to the British and their allies at Waterloo, now in present-day Belgium, and his fate was sealed. He lost power in France, never to fully regain his glory.

Meanwhile, the legacy of the Louisiana Purchase is an ongoing story. In 1803, American diplomat Robert Livingston predicted that the deal would allow the United States to “take their place among the powers of first rank.”

He would not be surprised, we think, at just how true his words turned out to be.