How did a shipwreck double the size of the United States?

King Carlos II of Spain was cousin to King Louis XV of France through the Bourbon bloodline. In 1762, Louis ceded the Louisiana Territory to Carlos with the Treaty of Fontainebleau. The land grant wasn't motivated by fond familial regard; Louis sought keep his precious Louisiana Territory out of British hands. The French had lost the Seven Years' War to the British, and King Louis foresaw the upcoming repercussions. The next year, Britain and France signed the Treaty of Paris that ended the war officially and gave the English all of Louisiana east of the Mississippi River -- except for New Orleans.

In 1682, explorer Robert Cavelier de La Salle discovered the mouth of the Mississippi near present-day New Orleans and named the land "Louisiana" in honor of King Louis XIV. De La Salle failed to establish a lasting settlement, but Pierre LeMoyne Sieur d'Iberville arrived 17 years later and started Fort Maurepas about 70 miles (112 kilometers) northeast of New Orleans. Hearing the news, King Louis XV granted permission to start a French colony, and New Orleans became the capital city in 1718.

New Orleans' geography had its share of pros and cons. Hordes of ]mosquitoes attracted to the waterlogged city's climate bred disease, including yellow fever and smallpox. Yet New Orleans was prime commercial real estate. Farmers and traders could send their goods down the Mississippi River to the Gulf of Mexico via New Orleans, then ship it anywhere in the world. Spain exploited its control over the port and levied expensive tariffs for its use. But those export profits didn't insulate New Orleans or the Spanish government from the loss of money that sank with El Cazador. As more people settled in the sprawling Territory, it became even more unwieldy -- and costly -- for Spain to manage.

Around that time, France started eyeing its former territory again. Napoleon took the French throne by coup in 1799, and he looked to the West to expand his empire. On Oct. 1, 1800, Spain and France signed the secret Treaty of San Ildefonso. With it, Napoleon cut a deal to give the King of Spain's son-in-law the Tuscan throne in exchange for returning the Louisiana Territory to French control. At the same time, trouble was brewing in French-owned Hispaniola that would indirectly alter the United States' fortune forever.

Napoleon dream­ed of creating a Western empire centered on international trade. The French Caribbean islands and Hispaniola (Haiti and the Dominican Republic) could farm sugar, coffee and tropical produce. With New Orleans as its trading stronghold in North America, Napoleon would wield economic power over the United States [source: Lachance]. However, a slave uprising led by Toussaint L'Ouverture in Saint-Domingue (the former name for Haiti) dashed those imperial plans.

The only successful slave revolt in history, French forces couldn't quell the Haitian rebellion. Napoleon dispatched 20,000 soldiers to restore peace and order, but a combination of yellow fever and unyielding solidarity among the former slaves defeated the military's efforts. By late 1802, France had lost an estimated 55,000 men [source: Lachance]. Since Saint Domingue was France's most lucrative colony in the West, Napoleon considered it a key asset for building his Caribbean empire [source: Rodriguez]. Cutting his losses, Napoleon abandoned the Western strategy and decided to refill France's dwindling treasury for impending war with Britain.

While Napoleon sorted out his imperial problems, another legendary leader also contemplated expanding his nation's horizons. President Thomas Jefferson viewed French control over the port at New Orleans as a hindrance to American settlement in the West. Jefferson didn't want to fight with France over the territory, instead seeking a diplomatic solution. He sent James Monroe as his envoy to the French government with an offer to buy New Orleans for no more than $3 million.

Instead of haggling over the port city, Napoleon surprised Jefferson by upping the ante. He put up the entire Louisiana Territory for sale -- no more, no less. The strict constructionist president was conflicted at first with the offer since the Constitution didn't include allowances for the federal government to accept land purchases. To get around that, he framed the deal as a treaty between the United States and France. The strategy worked, and Jefferson bought the enormous swath of land between the Mississippi River and the Rocky Mountains for $15 million on April 30, 1803.

Priced at barely four cents per acres, the 828,000 square miles (2.1 million square kilometers) signed over in Jefferson's Louisiana Purchase Treaty effectively doubled the size of the country. In less than three years, Louisiana passed from Spain to France to the United States. Though it took an unlikely shipwreck, war and a slave uprising to get there, Jefferson sealed the largest land deal in U.S. history with peaceful diplomacy and a signature.