The history of electricity is a long one, going back to about 600 B.C., when the Greek mathematician Thales of Miletus discovered static electricity by rubbing a piece of amber on a patch of cat’s fur. But some phases in electrical history were a bit more dramatic, and among the most suspenseful was a period known as “the war of the currents.”

It’s a story with so much intrigue that it’s often told outside of history class, most recently in the feature film, “The Current War” starring Benedict Cumberbatch and Tom Holland. But what kind of war was it?


The stage was set for the war of the currents in the late 1870s, when American inventor Thomas Edison developed the modern incandescent light bulb. Edison’s bulbs were powered via direct current (DC), which means the flow of electricity runs in one continuous direction. 

Edison’s goal was to bring indoor electric lighting to homes and businesses around the world, and he was devoted to DC electricity, a technology in which he owned several crucial patents. By 1882, Edison had opened the world’s first power plant in Manhattan, with a total of 82 connected customers. Not long after, Edison hired a young engineer by the name of Nikola Tesla, who had just emigrated from Serbia.

During Tesla’s time at the Edison Machine Works, he tried to convince Edison to invest in alternating current (AC) technology, with which Tesla had been experimenting for years. The flow of AC electricity reverses itself several times per second, which gave it distinct advantages over DC: AC could be transmitted over long distances without a significant loss of energy, it was easier to increase or decrease the voltage of AC electricity, and AC was cheaper to deliver. On the other hand, AC electricity is initially transmitted at much higher voltages than DC, which carried a higher risk of accidental electrocution.

Edison wasn’t persuaded, and after just a few months, Tesla quit his job and began pursuing his own AC technology patents.

Competition and Propaganda

Tesla struggled as an inventor for the next few years as Edison continued to promote and sell his DC power system and incandescent light bulbs. But Tesla’s AC technology eventually caught the attention of the industrialist and engineer George Westinghouse, who purchased several of Tesla’s patents for his Westinghouse Electric Company. 

Edison, meanwhile, was struggling to make his DC power economically viable. Fearing the encroachment of Westinghouse and Tesla’s AC on the electrical market, Edison began a messaging campaign to portray AC as dangerous. There was already a basis for stoking skepticism of AC among the public, as there had been some gruesome public deaths of electrical repairmen who were electrocuted while maintaining high-voltage AC lines. But Edison’s campaign stretched the truth beyond these accidents to paint AC in a more sinister light.

Colluding with an electrical engineer and AC critic named Harold P. Brown, Edison’s propaganda campaign included public displays in which animals were brutally killed by electrocution. Edison and Brown championed legislation aimed at limiting the voltage of AC installations under the guise of public safety, knowing that such a change would make AC unviable. The duo even successfully ensured that the first electric chair built in the United States was operated by a Westinghouse Electric Company AC generator.

The End of the War

The war over public messaging and technological rights raged on into the early 1890s, but Westinghouse’s AC electricity was destined to strike a decisive blow. In 1893, Westinghouse beat Edison in a bid to power the Chicago World’s Fair, proving that AC could get the job done cheaper and with less physical infrastructure. The spectacle of nearly 100,000 glittering lights captured the world’s imagination and helped cement AC as the electrical technology of the future.

Soon after, Westinghouse was awarded another major contract to build a hydroelectric power plant at Niagara Falls. When the plant and its high-voltage transmission lines were completed in 1896, the system transmitted stable electricity nearly 30 miles to Buffalo, New York. The achievements of the World’s Fair and the Niagara Falls plant ensured AC’s dominance, and the war of the currents was over.

Edison’s DC technology never went away, however, and is more important than ever today. That’s because DC electricity is what powers batteries, and batteries are what power many of the most essential devices we currently use, from smartphones to electric cars. So while AC won the war of the currents, AC and DC are both equally indispensable to our modern, electrified lives.