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During Persia's invasion of Greece under Xerxes, Ephialtes betrayed the bunch of Greeks at the very strong defensive position at Thermopylae by showing the Persians an alternate path around the pass. This led to the complete defeat of the Greek army and the death of the Spartan king Leonidas, and opening the way to the sacking of Boeotia and Athens. While I can see the argument that this was unsuccessful because the Persians ultimately lost the war, the fact that it gave the Persians control of a decent chunk of Greece for a year and that they lost for a wholly unrelated reason (mostly due to Salamis) would make this at least a short term success.
In the turmoil at the end of Qin, Qing Bu was one of the most important generals of Xiang Yu, who became the hegemon. After the fall of Qin, Liu Bang and Xiang Yu vied for the throne. Qing Bu later joined Liu Bang and attacked Xiang Yu in the rear, and was critical to the eventual defeat of the latter.
Towards the end of the Later Han, Liu Zhang was an independent governor of Yizhou. When he heard that Cao Cao intended to attack his northern buffer state of Hanzhong, he was convinced by his advisor Zhang Song to invite in Liu Bei to help protect Yizhou. However, both Zhang Song and Fa Zheng, who was sent to welcome Liu Bei, were secretly plotting to have him displace Liu Zhang. Despite initially protesting that he could not behave so treacherously to his own kin, Liu Bei eventually found an excuse to act. A number of other generals betrayed Liu Zhang during this conflict and Liu Bei was ultimately successful. Zhang Song didn't live to see it though. He lost his head when his brother informed Liu Zhang of his actions.
Upvote:-2
Successful treason examples. William the Conquer 1066 (when he landed in England he instantly became subject to its laws) Future Henry IV 1399. Future Richard III 1483. Future Henry VII 1485. Future William III 1688.
Upvote:1
Generally, its only called "treason" when the damage isn't mortal. Of course when it isn't mortal, The State has a whole lot more power to go after you than you have to stay out of its power. This is why Machiavelli observed that if you go after "The Prince" in any way, you have to kill him.
Basically, either The State falls, and you are considered a hero by the victors (who get to write history using nicer words for you) or The State doesn't fall, and going after you is its top priority for the rest of your life. So any list of successful treasons is going to have a caveat on either the word "successful" or the word "treason".
Upvote:1
Charles-Maurice de Talleyrand, prince de BΓ©nΓ©vent - the fellow who moved from supporting the King to the Revolution to Napoleon to the Restored Kings qualifies a half a dozen times.
John Churchill, later Lord Marlborough and his associates also betrayed the Catholic King James II to support William of Orange. This is called the Glorious Revolution by the winners, probably something less nice by James II.
Almost any regime change could produce a bunch of examples.
Upvote:4
Every government begins with a successful act of treason against the prior government. Most government reforms begin with an act that if not successful would be deemed treason.
There are limitless additional examples.
Upvote:9
British rule over the indian subcontinent started with a treason. Mir Jafar betrayed the local Nawab and went over to the Brits, paving way for the British Raj.
Upvote:12
As I have read many times, the founders of USA were conducting treason. Given that they declared independence, I guess that view can be upheld. They definitely switched sides (to their own, of course). They betrayed an Empire to do so, so I think all three conditions are met.
Upvote:17
John Harington Epigrams, book iv, Epistle 5:
Treason doth never prosper: what's the reason?
Why, if it prosper, none dare call it treason.