What was the dispute between Tesla and Edison really about?

It was a commercial fight over which system would electrify the world — direct current or alternating current — and it is usually told as a personal duel between two inventors when it was mainly a contest between two companies.

Nikola Tesla arrived in the United States in 1884 and worked briefly for Edison Machine Works before leaving within a year. Tesla later said he had been promised $50,000 for redesigning Edison's dynamos and was refused it; the story rests on his own account and has never been independently verified.

The substantive conflict came afterwards. Edison had built his business on direct current, which cannot be transmitted efficiently over long distances and needed generating stations every mile or so. Tesla's alternating current system, with transformers stepping voltage up for transmission and back down for use, solved that problem. Tesla sold his AC patents to George Westinghouse, and it was Westinghouse's company that Edison's interests actually fought.

The campaign that followed — the so-called war of the currents in the late 1880s and 1890s — involved public demonstrations intended to portray AC as lethal, including the electrocution of animals, and lobbying to have AC used for the first execution by electric chair. AC won regardless, on straightforward engineering grounds. It powers the grid today.

Tesla's later life was genuinely difficult. He held around 300 patents but was a poor businessman, and he died in a New York hotel room in 1943 in debt, though Westinghouse had quietly been covering his accommodation. The frequently repeated claim that he and Edison were jointly offered a Nobel Prize in 1915 is not supported by the record.