This article reconsiders the France's notification to China of the conclusion of the Saigon Treaty and its relationship with the Chinese military expeditions in Tonkin in northern Vietnam. It has been known that Qing government's response stating that Vietnam "had long been a tributary state (本係屬國)" of China was mistranslated by the French embassy in China as Vietnam "had been a tributary of China" (a ete tributaire de la Chine) and was interpreted as the Qing government's relinquishing of suzerainty over Vietnam, and as a result there were no hostilities between France and China for the time being, despite the fact that the independence of Vietnam was proclaimed in the treaty. Nevertheless, the French side regarded Qing military expeditions to Vietnam as demonstrating their suzerainty over Vietnam as problematic. How then was the problem of these military expeditions treated when notification of the Saigon Treaty was issued? This point has seldom been examined in previous scholarship. This article chiefly examines the actions of Comte Julien de Rochechouart, the French charge d'affaires in Beijing at the time and points out his deliberate actions were taken to satisfy the conflicting demands of the French and Qing governments regarding the problem of military expeditions. The Qing government actually sought an early withdrawal of its troops from Vietnam. However, as the expansion of French power in Vietnam was also not strategically desirable, it could not accede to French demands for a military pull out. When notification of the Treaty of Saigon was issued, de Rochechouart addressed the demand for troop withdrawals not to the army of Guangxi stationed in Vietnam but to the Yunnan army, which had not crossed the border into Vietnam. Although the Zongli Yamen was conscious of this "error, " it responded with a message that the Yunnan troops would not be allowed to cross the border. De Rochechouart spuriously reported to his government that the response was an acceptance of the demand for troop withdrawals. Thereafter, the Qing army completed its campaign in Tonkin and withdrew in accordance with its own predetermined policy. Regarding its own position satisfied, France took a stance maintaining the status quo and viewing the relationship between Qing and Vietnam as a "ritualized" ceremonial one. This led to relations between China and France that continued under a state of "mutual miscomprehension." However, later events forced the Qing government to once again dispatch troops and that resulted in the French reaction that subsequently developed into the "l'affaire du Tonkin." In researching this article, I have been able to prove that the mistranslation, which has been thought to be an error leading to war, was in fact a deliberate act intended to avoid the conflict.