You will be happy to hear of the success that has attended a detachment of this fleet under the command of Captain Martin, of the Implacable, in an attack on the Russian flotilla, by the boats of that ship, the Bellerophon, Melpomene, and Prometheus, under the orders of Lieutenant Hawkey, who succeeded in boarding and carrying off six gun-boats, besides one sunk, and a convoy of vessels, fourteen in number, which were also captured, laden with stores and provisions for the Russian troops. It is with concern I have now to state the loss of Lieutenant Hawkey, who conducted that attack; and Lieutenant Stirling of the Prometheus, Mr. Mountenay, a midshipman, besides ten men killed and thirty-seven wounded. The Implacable and Melpomene had, previously to this, nearly captured a large Russian frigate off Hoegland; but she escaped to Aspoe, and, with four other ships of war, proceeded between the rocks to Frederickshamn. On the following day they captured nine vessels laden with naval stores belonging to the Emperor, which they fell in with in Narva Bay. I anchored here last Sunday in expectation of procuring a supply of wood and water; of the former I found an abundance, which had been ready prepared for the Emperor's troops at Revel, but was disappointed in being able to obtain but a small supply of water. I am in anxious expectation of receiving favourable accounts from the armies. If Napoleon can but be defeated, the cause of Sweden will be materially benefited, and the Emperor of Russia kept within proper bounds. I am, &c. JAMES SAUMAREZ. One of the first acts of his Swedish Majesty after his coronation was to put into execution the intention of the former sovereign, by conferring on Sir James the Grand Cross of the honourable military order of the Sword for his past meritorious service. This was communicated to him in the handsomest manner; but the honour could not of course be accepted without the permission of his own sovereign, which, on application, was most graciously accorded. The news of the triumph of the British squadron over the Russian flotilla occasioned great rejoicing in Sweden, and inspired the nation with new spirit and courage: congratulations were sent from all quarters. Baron Platen sailed in the Rose from Daleroe on the 20th, and came on board the Victory on the morning of the 23rd under a salute of seven guns. In a letter to Mr. Foster, Sir James says: "Since the attack upon the gun-boats, not a vessel has been seen upon the coast; and I hope effectually to prevent any supplies getting to the Russian troops in Finland excepting over land, which must tend to retard all their operations exceedingly.