Top 10 Most Damaging Spy Missions in History

The Espionage Act of 1917 defined espionage as the notion of obtaining or delivering information relating to national defense to a person who is not entitled to have it. The Act made espionage a crime punishable by death, but there are always men and women willing to risk it — for country, for honor, or maybe just for some quick cash.

Whether they infiltrated the enemy's ranks or sweet-talked the details out of careless persons who ignore all those "loose lips sink ships" posters, these are the most notorious spies with the most successful espionage missions in history, ranked by the operations they disrupted, the damage they dealt, and the odds stacked against them.

10. Aldrich Ames — COLD WAR

Aldrich Ames is a 31-year CIA veteran turned KGB double agent. In 1994, he was arrested by the FBI for spying for the Soviets along with his wife, Rosario Ames, who aided and abetted his espionage. Following his arrest and guilty plea, Ames revealed that he had compromised the identities of CIA and FBI human sources, leading some to be executed by the Soviet Union.

During a nearly year-long investigation into his subterfuge — and his subsequent trial — it was revealed that Ames had been spying for the Soviets since 1985, passing details about HUMINT sources, clandestine operations against the USSR, and providing classified information via "dead drops" in exchange for millions of dollars.

It was, in fact, the Ames' lavish spending that finally led to their downfall, but by then, he had already nearly destroyed the American intelligence program in the Soviet Union.

Ames is currently serving his life sentence, while his wife, as part of a plea-bargain agreement, served only five years and walked free.

9. Virginia Hall "The Limping Lady" — WWII

Virginia Hall was one of the most successful espionage operatives of World War II, earning not only the contempt of the Gestapo, but the Distinguished Service Cross — the only civilian woman to be so honored. As a spy, she organized agent networks, recruited the local population of occupied France to run safe houses, and aided in the escape of Allied prisoners of war.

Oh, and she did it all with a wooden leg named 'Cuthbert.'

Known by the Nazis as "The Limping Lady," she was recruited by British spymaster Vera Atkins to report on German troop movements and recruit members for the resistance in France. Posturing as an American news reporter, she encoded messages into news broadcasts and passed encrypted missives to her contacts.

She signed up with the U.S. Office of Strategic Service and in 1944 she organized missions to sabotage the Germans. She is credited with more jailbreaks, sabotage missions, and leaks of troop movements than any other spy in France.

8. Harriet Tubman — CIVIL WAR

Everyone knows that Harriet Tubman helped slaves reach freedom through the Underground Railroad after her own escape in 1849. When the Civil War broke out 11 years later, she continued the fight by becoming a spy for the Union Army.

Though she was unable to read or write, Tubman was exceptionally bright. Her time spent with the Underground Railroad taught her to keep track of complex details and information, scout transportation routes, and arrange clandestine meetings.

She used these skills to build a spy ring, mapping territory, routes, and waterways, and collecting human intelligence about Confederate movements and weaponry. She was the first and only woman to organize a military operation during the Civil War, overseeing the transport of Union boats through Confederate-mined territory based on intel she had collected.

During the same raid, she helped to free 700 local slaves, 100 of whom would take up arms for the North.

7. George Blake — WWII-Cold War

George Blake was recruited to the Secret Intelligence Service, otherwise known as MI6, during World War II. During the Korean War, he was taken prisoner by the Korean People's Army, and during his three year detention he became a communist and decided to betray his country.

In 1953, he returned to Britain a hero, but secretly began his work as a double agent for the KGB, wherein he would compromise anti-communist operations and reportedly betray over 40 MI6 agents and dismantle MI6 operations in Eastern Europe.

In 1961, he was exposed by a Polish defector, arrested, and sentenced to 42 years of imprisonment, but in 1966 he broke out and fled to Moscow, where he was awarded the Order of Friendship by Vladimir Putin.

6. Agent 355 — AMERICAN REVOLUTION

There were several Patriot spy rings that worked to overthrow British occupation during the Revolutionary War, but very few of these secret groups had women who actively took part in the espionage. The Culper Spy Ring, however, is known mainly for a very unusual agent, a spy known then and now only as '355' — the group's code number for the word 'woman.'

The mystery woman's identity was kept secret to protect herself and likely her family, but her daring contributions to the American cause have been remembered in history. She took part in several counterintelligence missions, including spy operations that resulted in the arrest of major John Andrew — the head of England's intelligence operations in New York — and the discovery of Benedict Arnold's treason.

Some historians guess that Agent 355 was likely a shopkeeper or a merchant who learned information about Red Coat military operations from chatty British customers, and that she would then divulge this information to George Washington. Regardless of her methods, Agent 355 made critical contributions to the Revolutionary cause.

5. Rose Greenhow — CIVIL WAR

Confederate spy Rose Greenhow is credited with obtaining critical intelligence about the Union's plans to attack in Manassas, Virginia. She established her spy network in Washington DC at the beginning of the Civil War, and it quickly proved its worth when Greenhow uncovered details about Union General Irvin McDowell's plans in 1861. Greenhow spirited intelligence to Confederate General Pierre G.T. Beauregard, who requested extra troops when he met Union forces at Bull Run on July 21st.

The Battle of Bull Run was the first major land battle of the Civil War and, as a result of Greenhow's intelligence, the South was able to achieve a major victory and launch their rebellion with momentum. Confederate President Jefferson Davis himself sent Greenhow a letter of appreciation after the battle.

Federal authorities were soon able to trace Greenhow's activities, however, and she was placed under house arrest before an incarceration in the Old Capitol Prison. After her release, she would continue to fight for the Southern cause until her death at sea while transporting Confederate dispatches aboard a British blockade-runner.

4. Oleg Gordievsky — COLD WAR+

Oleg Gordievsky has been given credit for shifting the balance of power during the Cold War. For 11 years, he spied for MI6 while working as a high-ranking KGB officer in London. In 1968, Gordievsky was a junior spy working abroad for the KGB when the Soviet Union invaded Czechoslovakia.

He resolved himself to fight the communist system from within. In 1972, Gordievsky was recruited by MI6 after he was referred by a Czech spy who had defected to Canada.

Over the next decade, Gordievsky would provide details of current and former KGB operations as well as the KGB's attempts to influence western elections. He was exposed to Moscow by Aldrich Ames and managed to survive a KGB interrogation despite being drugged. MI6 managed to recover Gordievsky and smuggle him safely out of the country.

He is one of the highest-ranking KGB officers ever to operate western espionage missions and for this he was sentenced by Soviet authorities to death in absentia.

3. Francis Walsingham — TUDOR ENGLAND

Most spies work in secret, but Francis Walsingham served Queen Elizabeth I with the badass title of Spymaster. A staunch Protestant, Walsingham served as Principal Secretary of State for the Tudor queen before joining her Privy Council, where he devised an intricate spy network during her reign. He uncovered what became known as the Babington Plot of 1586, which lead to the execution of Mary, Queen of Scots the following year.

Encouraged by her supporters, Anthony Babington wrote a letter to Mary concerning "the dispatch" of Queen Elizabeth during Mary's incarceration in England. Mary's reply was intercepted by Walsingham and Thomas Phelippes, who copied the letter and forged a damning postscript to the end. Walsingham used the copied letter and the cipher text of the original to convince Elizabeth that for as long as Mary lived, she posed a threat to the Protestant throne.

Elizabeth reluctantly signed Mary's death warrant and she was beheaded on February 8, 1587. Elizabeth safely reigned until her own death in 1603.

2. Robert Hanssen — COLD WAR+

Former FBI agent Robert Hanssen spied for Soviet and Russian intelligence services from 1979 to 2001 and remains one of the most damaging double agents in American history. His espionage activities included delivering thousands of pages of classified material to Moscow, revealing the identities of human sources and agents and details about America's nuclear operations.

One of his first acts as a Soviet spy was to expose Dmitri Polyakov, a Soviet general and CIA informant who was then executed. During his espionage tenure, he would receive over $1.4 million in cash and diamonds to betray his country.

The FBI discovered Hanssen's treachery and he was indicted on 21 counts of spying for the Soviet Union and Russia. He would finally plead guilty to 15 counts of espionage and conspiracy in exchange for 15 consecutive life sentences in prison over the death penalty.

1. The Rosenbergs — COLD WAR

Julius and Ethel Rosenberg were the first U.S. citizens to be convicted and executed for espionage during peacetime after they were found guilty of delivering classified information about the atomic bomb to the Soviet Union. Julius was an engineer for the U.S. Army Signal Corps and his wife Ethel worked there a secretary.

In 1950, they were implicated by David Greenglass, Ethel's younger brother, who worked at Los Alamos, a secret atomic bomb laboratory in the States and who confessed to providing classified intelligence to the Soviets.

The Los Angeles Times reported that not only did the Rosenbergs do "their best to give the Soviets top atomic secrets from the Manhattan Project, they succeed in handing over top military data on sonar and on radar that was used by [Moscow] to shoot down American planes in the Korean and Vietnam Wars."

After a controversial trial and global speculation, they were executed via electric chair on June 19, 1953. 

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