Traitors within the military are among the most reviled figures in history – however, they also captivate our interest. It’s baffling to contemplate how someone could betray their country and directly endanger those who were once their comrades. Motivations vary; some are driven by financial gain, others by a desire for revenge and many by sheer narcissism. However, once they switch sides, they often find themselves shunned; if they can betray their kin, they can betray anyone.
Below is a list of the most notorious traitors in military history, commencing with the American Revolution.
Benedict Arnold
Benedict Arnold stands out as one of the most notorious military turncoats in history. Initially, he showcased bravery as an officer in the Continental Army during the American Revolution. However, feelings of being overlooked for promotions, despite his valor and enduring severe injuries, led to disillusionment.
Despite the trust placed in him by George Washington, Arnold’s disenchantment with the revolutionary cause grew. In 1780, he defected to the British side, offering to surrender West Point in exchange for a commission as a general in the British Army. While the British never seized control of West Point, Arnold’s betrayal marked a significant blow to the Continental Army as he fought against his former comrades as a brigadier general.
In modern-day America, Benedict Arnold’s name is synonymous with treachery and betrayal.
Alfred Redl
Alfred Redl, the second individual on our list of military history’s biggest traitors, was the head of the counter-intelligence branch in the Austro-Hungarian Army, having pioneered counter-espionage techniques. Between 1903-13, he secretly worked as a spy for the intelligence service of the Imperial Russian Army, using his position to hand over extremely valuable documents.
Over the course of his spying career, Redl gave the Russians the entire Austrian invasion plan for Serbia, military plans, doctrines, tactics and strength. He also used his position to provide the names of agents working as spies against Russia. Even worse, he sent some into Russia, only to then inform Russian authorities of their presence.
Redl is believed to be responsible for the deaths of tens of thousands of Austrians during the First World War, and he is thought to have been part of the reason behind Austria-Hungary’s poor military performance during the conflict. In 1913, he was outed as a spy using his own techniques, at which point he took his own life.
Harold Cole
A petty criminal, thief and fraud, Harold Cole is among the most notorious and biggest military traitors in British history. During the early years of the Second World War, he worked alongside the French Resistance, helping soldiers and downed pilots return to England via escape lines through German-occupied France. He was a prominent member of the organization, but eventually betrayed members to the Gestapo in late 1941.
He handed over the names of around 150 people working along the escape lines and/or for the French Resistance. Approximately 50 of them were either executed or died in concentration camps.
Over the course of the war, Cole was wanted by the British, Germans and French. He was killed in a gunfight with French police in 1946, after resisting arrest, and is now considered among the “most selfish and callous traitors who ever served the enemy in time of war.”
Robert Hanssen
Described as “possibly the worst intelligence disaster in U.S. history,” the actions of traitor Robert Hanssen are the most recent on our list. He was an FBI agent from 1976 to 2001, and spent most of that time selling top-secret information to the Soviet Union and, following the USSR’s collapse, the Russians.
He leaked information about US spy equipment, such as radar and spy satellites, and also revealed the names of agents spying on the Soviets. Hanssen famously informed the USSR about a highly-secret eavesdropping tunnel built under the Soviet Embassy by the FBI.
On one occasion, he was tasked with identifying a mole within the FBI. Unbeknownst to his superiors, the individual was actually himself, which made it easy for him to cover his tracks. Hanssen remained anonymous throughout his career, and it was only on February 18, 2001, after a long investigation, that the FBI discovered he was a spy and arrested him.
On June 5, 2023, Hanssen, then 79, was found unresponsive in his prison cell at the ADX Florence supermax prison in Florence, Colorado. He was later pronounced dead, with the Associated Press speaking to an anonymous source, who said he’s believed to have died of natural causes.
Wang Jingwei
The final entry on our list of the biggest military traitors in history is Wang Jingwei. He was a leftist politician in pre-Communist China who often clashed with his rival, Chiang Kai-shek.
Toward the beginning of World War II, Wang made a deal with Japan to hand over Nanjing, in return for him being given a puppet government that would be run in collaboration with the Japanese Empire. He died just before the end of the conflict.
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Once Japan was defeated by the Allies, Chiang’s government returned to Nanjing, where they destroyed Wang’s tomb and burned his body.