Before Fort Sumter fell in 1861, Stephen Duncan was the richest man in America.

He owned 15 plantations, enslaved hundreds of people, and was America’s largest cotton producer. His liquid investments alone were worth more than $1 million ($200 million today). Fully valued and capitalized like a corporation, Duncan was probably America’s first billionaire.

That’s because back then, the world’s economy didn’t run on crude oil. It ran on cotton.

The American South grew roughly 80% of global cotton. Britain bought virtually all of it. England held two-thirds of the world’s mechanical spindles, making the textiles that clothed the world. Textiles were more than half of British exports. And 25% of Britain’s population depended on the textile trade.

Nearly all of this commerce passed through one market: Liverpool. About 140 cotton brokerages worked around the Liverpool Cotton Exchange. A bale might change hands 10 times before reaching a mill in Lancashire.

And then, the U.S. Civil War.

Much like Iran’s mullahs today view oil, the Confederacy’s politicians believed Britain could not live without cotton. They embargoed their crop to force London to recognize the Confederacy. American cotton arrivals at Liverpool fell from 166,000 bales in July 1861 to 35 bales in September. Cotton exports from America to Europe fell from 3.8 million bales in 1860 to almost nothing in 1862.

New Orleans cotton sold for 7¾ pence per pound in June 1861. By 1863, it cost 29 pence. British mills cut consumption by more than half. In November 1862, 412,830 Lancashire workers were unemployed or working reduced hours, and more than 250,000 people required relief. Britain searched everywhere for substitutes, and imports from India tripled while their price quadrupled. Indian cotton was shorter, dirtier, and harder to spin: more than one-sixth of the cotton reaching British mills in 1862 could not be used and shipping it to Liverpool took four to six months.

Notice the pattern: unemployment soared, prices increased by 4x, refining costs rose, and shipping became vastly more expensive too.

As we first explained in March, a war with Iran is a threat to the global economy.

Virtually all the world’s transportation networks depend on crude-oil fuel stocks, from which diesel fuel and Jet A are refined. The Persian Gulf normally sends roughly 20 million barrels of crude oil and refined products through the Strait of Hormuz each day, about 20% of the world’s total production. About 80% of this crude oil goes to Asia. Before the war, the Gulf also shipped about 900,000 barrels of diesel and 350,000 barrels of jet fuel each day. Those volumes represented roughly 10% of seaborne diesel and 20% of seaborne jet fuel.

The first phase of the war cut Hormuz oil flows to 2.7 million barrels a day from March through May. The Gulf producers then found partial escape routes: Saudi exports through the port city of Yanbu rose from 2 million barrels a day before the war to more than 5 million by early June, while the United Arab Emirates filled its 1.8-million-barrel-a-day line to Fujairah on the Gulf of Oman.

Some crude is moving again, but how much? The available official and commercial counts do not agree.