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The War of the Currents: A Battle of Patents and Power

The War of the Currents was a historic feud in the late 19th century between inventors Thomas Edison and Nikola Tesla. The crux of the battle revolved around the most efficient method to distribute electricity—Edison’s direct current (DC) versus Tesla’s alternating current (AC). While Edison’s DC systems were initially standard, they were found to be less effective over long distances, causing Tesla’s AC to eventually dominate as the preferred standard. This period was marked by heated public relations campaigns, patent battles, and technological innovations that would shape the future of electric power distribution.

Thomas Edison and Nikola Tesla

Edison and Tesla, the two remarkable figures at the heart of the War of the Currents, were inventors par excellence of their time. 

Thomas Edison, known as the “Wizard of Menlo Park,” held 1,093 patents for his inventions. Edison’s inventions, including the phonograph, the motion picture camera, and improvements to the electric light bulb, profoundly influenced life around the world. His ingenuity and perseverance have become legendary, making him a quintessential American inventor.

In contrast, Nikola Tesla, the “Master of Lightning,” was a Serbian-American inventor, electrical engineer, mechanical engineer, and physicist. Known for his design of the modern alternating current (AC) electricity supply system, Tesla’s work laid much of the groundwork for modern electrical and communication systems. Though he was largely unrecognized during his lifetime, Tesla’s influence has grown posthumously, with his achievements earning him a place as one of the great pioneers in electrical engineering.

Edison’s contribution to the Direct Current (DC)


Thomas Edison’s pivotal contribution to the Direct Current (DC) system was his establishment of the first electrical power station, Pearl Street Station in lower Manhattan, in 1882. This revolutionary station was designed to supply electricity to customers within a square mile area using his DC system. Edison’s DC system had the advantage of being safe at low voltages and could power light bulbs. However, it had a significant limitation, the power plants could only supply electricity within a 1 to 2-mile radius due to power loss during transmission at greater distances. Despite this shortcoming, Edison’s work laid the foundation for the development and deployment of electrical power systems, and his contribution to the DC system has allowed it to remain relevant even today, being used in batteries, solar panels, and electric vehicles.

Tesla’s contribution to the Alternating Current (AC)

Nikola Tesla’s contribution to the Alternating Current (AC) system was monumental. He developed a polyphase AC induction motor in 1887 and demonstrated its practicality for efficient power generation and transmission. This invention was revolutionary, as it overcame the primary limitation of Edison’s DC power – the inability to transmit over long distances. The AC system allowed for the power to be transmitted over great distances due to its ability to change voltage levels easily. Furthermore, Tesla’s polyphase AC systems introduced the concept of a rotating magnetic field, which laid the foundation for most machines that require rotational motion. Ultimately, Tesla’s work on the AC system has profoundly impacted modern power generation and distribution, with alternating current becoming the global standard for power transmission.

The War Begins

The War of the Currents officially began when George Westinghouse, an entrepreneur and engineer, bought Tesla’s patent for the AC induction motor and the polyphase system. Recognizing the potential of this invention, Westinghouse decided to promote the use of AC for electric power systems. On the other hand, Edison, financially invested in DC, began a hard-hitting campaign to discredit alternating current. The media was roped in, public demonstrations were held showing the dangers of AC, and an electric chair was built to show the fatal dangers of the alternating current. With the public’s safety at apparent risk, the battle lines were drawn, and the War of the Currents ensued, a war that was as much about technological superiority as it was about business interests and personal egos.

Edison’s campaign against AC 

Edison’s campaign against AC was ruthless and fearmongering in nature. Recognizing that his direct current system was losing ground to Westinghouse and Tesla’s AC system, Edison resorted to a publicity war. He aimed to convince the public that AC was dangerous and could lead to accidental electrocutions due to its high voltage. To prove his point, Edison staged public demonstrations known as “Death by Westinghouse” where he electrocuted stray animals using AC to show the “lethal” properties of the current. He even went so far as to support the development of the electric chair using AC power as a method of execution to underline the danger of AC. Edison’s campaign, while shocking, was ultimately unsuccessful in halting the progress of AC. His methods have been criticized for their cruelty and misrepresentation of the true nature of alternating current.

Tesla’s defense and promotion of AC

Unlike Edison, Tesla chose to counter the fear-mongering tactics with demonstrations of the safety and efficiency of AC. He conducted a series of lectures and public demonstrations to educate the public on the benefits and safety of AC. His most notable demonstration was at the World Columbian Exposition in Chicago in 1893, where he used AC to light the entire fair. This not only showcased the potential of AC but also its relative safety. One of Tesla’s most famous displays of the safety of AC was when he famously sent alternating current through his own body to produce light, demonstrating that it was safe for humans. Through these demonstrations and his unwavering belief in the superior technology of AC, Tesla played a pivotal role in the acceptance and implementation of alternating current, which has since become the global standard for power transmission.

The Turning Point

George Westinghouse was an integral player in the War of the Currents. His role, however, extended far beyond simply being a financier. Westinghouse was an accomplished American entrepreneur and engineer in his own right, credited with numerous innovations in the field of electricity and transportation. Renowned for his many inventions, he held over 360 patents in his lifetime. Westinghouse’s steadfast belief in the superiority of Alternating Current (AC) led him to purchase the patents for Tesla’s induction motor and polyphase system, setting the stage for the epic battle between AC and Direct Current (DC). Westinghouse’s vision, coupled with Tesla’s technological expertise, would eventually propel AC to being the global standard for power transmission.

Westinghouse’s support for AC was unwavering and strategic. He recognized the inherent benefits of AC, such as its efficiency and the ability to transmit electricity over great distances, which made it a more economical and practical choice for large-scale power distribution. Westinghouse’s support was not only verbal; he demonstrated his commitment by investing heavily in Tesla’s AC technology. He provided Tesla with the resources and platform to demonstrate the practicability of AC, which played a crucial role in winning the War of the Currents. Westinghouse’s belief in AC and his relentless advocacy for it was instrumental in driving its adoption, leading to the electrical infrastructure we see today.

The Chicago World’s Fair: Triumph of AC

The Chicago World’s Fair, also known as the World’s Columbian Exposition, marked a significant victory in the War of the Currents. George Westinghouse and Nikola Tesla won the contract to light the fair, a feat made possible by the AC system’s ability to transmit electricity over long distances. Over 27 million people attended the fair, witnessing the brilliance of the lights powered by alternating current, a display that far surpassed anything achievable by the direct current system. This event was pivotal in demonstrating the practicality and safety of AC, effectively marking the end of the War of the Currents and setting the stage for AC to become the preeminent standard for power transmission worldwide.

Effect on Patent on Law Going Forward 

The War of the Currents had significant implications for patent law going forward. It highlighted the importance of patents in the world of technology and innovation. Both Edison and Westinghouse understood the value of owning patents to protect their respective technologies. This high-stakes battle amplified the importance of patent rights and led to increased awareness about intellectual property among inventors and businesses. It also underscored the crucial role of patent law in fostering competition, driving innovation, and promoting economic growth. This historical event, therefore, served as a catalyst for a more robust and comprehensive patent system.


The War of the Currents was more than just a dispute between two technologies; it was a significant turning point in the history of electrical engineering that shaped the future of power transmission across the globe. This historic event unfolded at the intersection of scientific discovery, technological innovation, and relentless ambition. It saw the clashing visions of two remarkable inventors, Tesla and Edison, and how their fierce competition paved the way for the development of modern power systems. The triumph of AC demonstrated the importance of adaptability, strategic alliances, and foresight in the realm of technological advancement. It’s a testament to the notion that the best ideas, no matter how revolutionary or contentious they might initially be, can eventually win acceptance if they truly hold the merit of practicality and efficiency. Furthermore, the War of the Currents underscores the far-reaching impacts of technological decisions, which resonate across time and continue to shape our world today.