HISTORY’s new late-night series isn’t afraid to tackle tough issues. On the next episode of Join or Die with Craig Ferguson, he and his celebrity panelists will debate the rivalries that shaped the course of history. Take Nikola Tesla and Thomas Edison: Together, these geniuses lit the pathway to our modern world. In the process, they became foes. Plenty of blows were exchanged between Edison and Tesla—including some blatant cheap shots. Yet, beneath the vitriol, there was a mutual respect that never dissipated. At any given moment, either man was liable to act like his colleague’s biggest fan—or his arch-nemesis. Read on for more about their fascinating relationship.

1. EDISON GAVE TESLA HIS FIRST AMERICAN JOB 

You’d be hard-pressed to name an immigrant whose first few days in the U.S. were more eventful than Tesla’s. A native of Croatia, the young engineer—who was employed by one of Edison’s factories in Paris—immigrated to America at age 28 after one of Edison’s close associates recommended him for a job there. On June 6, 1884, Nikola Tesla arrived in New York City, and made a beeline for the American offices of Thomas Edison, a personal hero whom he hoped to impress. Before long, an opportunity struck.

The Edison Company had a difficult chore on its hands. Recently, it had installed dynamo generators on what was then the world’s fastest transatlantic passenger ship—a 518-foot marvel called the SS Oregon. When these failed, the liner’s upcoming departure had to be postponed. Enter Tesla. Back in Europe, he’d acquired some experience in fixing this sort of generator. As such, the Croatian was confident that he could repair the Oregon’s. Seizing the moment, Tesla volunteered to do so. With a team of Edison men, he slaved away long into the night. His resolve paid off: Under Tesla’s guidance, the crew was able to mend the dynamos and the Oregon left harbor on June 7.

According to Tesla’s version of events, the victorious new arrival went for a 5 a.m. walk down Manhattan’s Fifth Avenue. There, whom should he encounter but Thomas Edison himself? At the older inventor’s side was the associate who had recommended Tesla, a man by the name of Charles Batchelor. Spotting Tesla, Edison remarked, “Here is our Parisian running around in the night.” Tesla then announced that he’d just fixed the Oregon dynamos. Stunned, Edison walked away without a word. As he left, the immigrant heard him mutter, “Batchelor, this is a damn good man.”

2. TESLA CLAIMED THAT EDISON CHEATED HIM OUT OF A SMALL FORTUNE

Tesla spent six months with Edison Machine Works. Years later, the tinkerer boasted that he’d show up every day at 10:30 a.m. and wouldn’t go home until five o’clock the next morning. “I have had many hard-working assistants,” Edison reportedly once declared, “but you take the cake.”

Supposedly, their falling out began with an irresistible offer. According to Tesla’s autobiography, one of his managers (possibly Edison) told him that if he could find a way to improve the company’s direct current generators, he’d be rewarded with $50,000—the equivalent of $1.25 million today. Tesla agreed and devised no less than 24 successful upgrades.

However, he never got his promised 50 grand. To his great dismay, Tesla learned that the offer hadn’t been a serious one. Edison—again, according to Tesla—said, “When you become a full-fledged American, you will understand an American joke.” Instead, Edison proposed a $10 raise. His pride injured, Tesla refused and resigned. 

3. THEIR PROFESSIONAL RIVALRY SPAWNED THE FIRST ELECTRIC CHAIR

The two men were at the forefront of the (in)famous “War of Currents.” For decades, Edison had relied on a form of electric transmission known as direct current (DC). Yet this wasn’t the only available option. Alternating current (AC) could actually be sent over longer distances and, thus, its distribution required fewer generators.

Tesla had studied AC as a student at the Austrian Polytechnic School in Graz. After leaving Edison’s employ, he sold seven AC motor-related patents to industrialist George Westinghouse. Hoping to promote his own DC products over Westinghouse and Tesla’s new devices, Edison launched a smear campaign of epic proportions. According to Westinghouse, Edison once said that, “Direct current was like a river flowing peacefully to the sea, while alternating current was like a torrent rushing violently over a precipice.” In other words, AC was fundamentally unsafe—or, at least, so claimed Edison.

To sway the public, Edison quietly helped New York State build the first electric chair—using a Westinghouse AC generator. On August 6, 1890, it was used to execute convicted murderer William Kemmler. Westinghouse was horrified by the method, which proved not to be quick and painless at all. But, in the end, he and Tesla prevailed. By the mid-1890s, Edison caved and (like the rest of America) embraced AC.

4. THE MEDIA WAS CONSTANTLY COMPARING THEM 

The press couldn’t help but weigh each of the celebrity scientists against the other. “Who is king, Edison or Tesla?” asked one 1895 article. A year prior, newspaperman Arthur Brisbane had cheered Tesla as “Our Foremost Electrician … Greater Even Than Edison.”

Gossip about the pair always made for attractive headlines. In 1915, one report claimed that Tesla and Edison had been chosen to share the Nobel Physics Prize. This was flatly untrue. The Nobel Foundation said as much, calling the report “ridiculous.” (In fact, Tesla hadn’t even received a single nomination.) Yet, the rumors kept on swirling. To this day, some falsely believe that Tesla and Edison didn’t get this prize because the former wouldn’t share it with his longtime adversary.   

5. WHEN TESLA’S LAB BURNED DOWN, EDISON CAME TO THE RESCUE 

On March 13, 1895, disaster reared its ugly head. By 1895, Tesla had established a laboratory occupying the entire fourth floor of a six-story complex in Manhattan. There, he experimented with advanced motors, radio technology, and other world-changing projects. On March 13 of that year, a fire broke out, reducing the whole building to a pile of rubble. As if this setback weren’t grave enough, Tesla’s lab hadn’t been insured.

Edison—of all people—lent a helping hand. The younger scientist was given permission to temporarily continue his research in an Edison workshop at Llewyn Park, New Jersey. Tesla went on to secure a new lab for himself the following year.

6. PRIVATELY (AND SOMETIMES PUBLICLY), THEY PRAISED EACH OTHER  

In May of 1896, Edison learned that one industry journal was getting ready to release an article which would denounce both Tesla and himself. Using his considerable influence, the businessman stopped the piece from ever running. “[As] far as I’m concerned,” he wrote the editor, “I do not care what is said, but Tesla is of a nervous temperament and it will greatly grieve him and interfere with his work.” In the same letter, Edison saluted his colleague, opining that, “Tesla is an experimenter of the highest type, and may produce in time all that he says he can.”

The admiration was mutual. Years later, Tesla delivered a speech before the American Institute of Electrical Engineers. Discreetly, Edison snuck into the audience. Spotting Edison, Tesla, according to one historian, encouraged the audience to give the older man a round of applause.

7. … HOWEVER, WHEN EDISON DIED, TESLA CRITICIZED HIS RESEARCH METHODOLOGY

“Genius is one percent inspiration and ninety-nine percent perspiration.” Edison lived by this motto right up until the end. On October 18, 1931, he passed away in his New Jersey home at the age of 84. One day later, Tesla’s thoughts on his foe/ally turned up in on the editorial pages of a national newspaper.

“If he had a needle to find in a haystack he would not stop to reason where it was most likely to be, but would proceed at once, with the feverish diligence of a bee, to examine straw after straw until he found the object of his search,” wrote Tesla. “... I was almost a sorry witness of such doings, knowing that a little theory and calculation would have saved him ninety per cent of his labor.”

Catch a new Join or Die with Craig Ferguson this Thursday, February 25 at 11/10c on HISTORY. For a close look at another epic rivalry, click here to see why John Adams and Thomas Jefferson deserve the title of “History’s Greatest Frenemies.”