Following the Battle of Toba-Fushimi in the Boshin War, Tosa Domain's 6th Division under the command of Miura Inokichi Motoaki was sent by the new Meiji government to garrison the port of Sakai in Izumi Province, which had until that time been under the control of the Tokugawa shogunate's Osaka machi-bugyō.

Complaints soon reached the ears of the Tōsa samurai responsible for security that the sailors had become unruly, intruding into temples and homes without invitation, harassing women, and frightening the merchants.

However, due to strong protests by the French captain Abel-Nicolas Bergasse du Petit-Thouars, Roches made a strong ultimatum to the Japanese government with five demands:[2] At that time, the Western powers had numerous warships in Osaka Bay in connection with the unsettled political condition in Japan and the recent opening of Hyōgo port to foreign commerce, whereas the fledgling Meiji government had the bulk of its military forces hundreds of kilometers away in the Kantō region due to the ongoing Boshin War.

On the following day Captain du Petit-Thouars, commander of the Dupleix, landed at Sakai to witness the execution of two officers, a subaltern, and 17 Japanese soldiers, condemned to death as the principal authors of the aggression.

Captain du Petit-Thouars then seeing that the Japanese Government was decided on carrying out its engagements to the end, and ceding to a feeling of humanity, stayed the execution, declaring that he considered the reparation sufficient, and that he proposed to ask the Minister of France to intercede for a commutation of punishment in favour of the other condemned.

On March 17, Prince Yamashina Akira, together with Date Munenari, went aboard the French flagship Venice, formally apologized to Roches and extended an invitation to an audience with Emperor Meiji.