The year 1715 was marked by new Russian victories in the Northern War. The unit of Captain Pyotr Bredal, three frigates and a snow captu-red three Swedish ships during a desperate fight in the open sea. In response, the Swedes attempted to engage the Russian ships at Revel, but failed. New victories nearly always meant new allies. Thus, England and Holland, interested in seaborne trade with Russia, sent a large convoy of merchant vessels and an escort squadron to the Baltic. Exploiting his success and the favorable position it gave him, Peter next decided to organize an allied Russian-Danish landing at Sconia, a southern province of Sweden.
In the summer of 1716 the Russian fleet, now concentrated off the Danish coast, was joined by Danish, British and Dutch ships. The allied armada was under the command of Peter I, who hoisted his ensign on the stellar ship of the Russian fleet, the 64-gun Ingermanland. The Russian force included frigates, small cruisers and eighteen ships of the line.
The allied armada set sail for Bronholm. Fearing that engagement with such a strong fleet would prove unsuccessful, the Swedes blockaded themselves in Karlskrona. Although final victory was at hand, considerable discord prevented the allies from bringing their mission to a successful conclusion. The summer of 1716 was not blessed by victory: the landing operation in Sweden did not take place, and the Northern War continued.
Moreover, Charles XII died in December 1718, putting an end to the peace negotiations which had already begun. England, now anxious over the obvious strengthening of Russia's position in the Baltic, took up the side of the Swedes and volunteered to defend their interests with the backing of the English fleet.
It was difficult to stop the Russian forces which, by this time, were firmly established in the Baltic. The Russian fleet had become so powerful that it could now challenge the Swedish fleet on the open sea. In May 1719 Captain Naum Sinyavin left Revel with a group of six ships of the line and a snow to intercept a Swedish unit. On 24 May, the adversaries met not far from Osel Island. Sinyavin, aboard the 52-gun Portsmouth, supported by Captain Konon Zotov on the Devonshire, resolutely attacked the flagship of Swedish Commodore Wrangel. In the fierce fight that ensued, the Portsmouth, despite the loss of sails, managed to hit the 34-gun Swedish frigate Karlskrona Vapen with a fore-and-aft salvo, forcing her to surrender. When the Swedish flagship, the 52-gun ship of the line Wachtmeister, attempted to escape from the Russians, Captain Iakov Shapizo commanding the Raphail and Lieutenant-Commander John Delyap of the Hyagudiil were sent in pursuit. The bloody ensuing fight continued until the Russians overcame the Swedish flagship and forced her to strike her colours. Aboard the captured ships were approximately 110 killed and wounded. Sinyavin's feat went down in history, and the battle of Osel Island became the first victory of the Russian fleet on the open sea.
Sinyavin was himself promoted to the rank of Captain-Commodore.
The following year the Swedes attempted to strengthen their position in the waters of the Aland Archipelago. However, the attempt resulted in defeat for Sweden. At the end of July 1720 near Grengam Island the galley fleet of General Mikhail Golitsyn engaged the detachment of Vice-Admiral Eric Sjoblad. Sixty-one Russian galleys and twenty-nine island boats set out against a Swedish ship of the line, four frigates and several smaller craft. Yielding to the enemy's superior artillery power, Golitsin's fleet retreated to the skerries. The Swedes started in pursuit of the Russian vessels, but Golitsyn, a shrewd and experienced officer, enticed the enemy into a disadvantageous position and seized his opportunity. The granite coastal boulders, in effect, came to Golitsyn's aid; two Swedish frigates were run against them, seized and boarded. The Swedes realized their mistake and began to retreat, but it was already too late. The Russian galleys chased the Swedish vessels and in a savage fight succeeded in defeating two more frigates. An attempt was made to overtake the flagship of the Swedish force, and Admiral Sjoblad himself was fortunate to escape on the damaged 52-gun Pommern.
The Battle of Grengam in the skerries became an important page in the history of the Russian fleet. The Swedish 34-gun frigate Stor Phoenix, the 30-gun Vainqueur, the 22-gun Kiskin and the 18-gun Danska Orn were all taken captive. The Russian forces suffered losses of 285, while the Swedes recorded 510 casualties.
In 1721, the final year of the Great Northern War, Russian galleys ravaged towns along the coast of Sweden in a series of raids. It was now clear that the Kingdom of Sweden was no longer the dominant power in the Baltic Sea, a position the Swedes had enjoyed since the days of the Vikings.