In 1834, Vietnamese and Cambodian forces succeeded together in driving the Siamese out of Cambodia, and King Chan, who had fled to Vietnam (see this post) was able to return to Phnom Penh.
In his A History of Cambodia, historian David Chandler writes that “When Chan returned to his battered, abandoned capital in early 1834, he found himself under more stringent Vietnamese control. Thai successes in their overland offences had shown Minh Mạng that he could not rely on the Khmer to provide a ‘fence’ for his southern and western borders. With the defeat of the rebellion, he now moved to intensify and consolidate his control.” (123-24 1st ed.; 149-50 4th ed.)