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.