Rear-Admiral Stirling had been deprived of his two main steamships, Encounter and Barracouta, by orders of the Admiralty in March 1855, and did not receive them back until late June, though he then also received another ship, Pique. He was also joined by two more ships, the French Constantine (30 guns), and La Sybille (40 guns), giving him a suddenly considerably larger force. He also had a complex problem before him.

There was not much Stirling could do in regard to the major part of the problem, which was to find out what was going on at the mouth of the Amur, and if possible stop it, until the ice broke up in late April or in May. He knew of the wreck of the Diana at Shimoda by early April at the latest, because he referred to it in instructions to his captains, but he also knew that the crew were still alive and active, and so they had to be watched for. He knew that Admiral Putiatin had succeeded in making a treaty with the Japanese government, and he very much wanted to know what was in it, both for his own purposes and for his government's. His own concern in concluding a treaty had been to ensure that Japan did not favour Russia in the war; he could assume that the Russians had the same concern and priority in reverse; the terms were therefore of interest, particularly in regard to the ports which the Russians might use.