Peace was more common than war in the Baltic from 1721 to 1814 but there were also long periods of tensions and diplomatic and military preparations for war. Europe during this period was involved in almost constant negotiations about alliances and alignments between the various powers shifted frequently. Historians have tried to analyse this as various systems of power relations. In a long-term perspective, it seems difficult to discern any `systems’. It is rather the repeated changes which set the pattern – the `system’ was fluid, unpredictable and consequently not a great source of security, especially for secondary powers. Every state had to be prepared for anything and that kept the cost of maintaining armies and navies at a high level. The three Baltic powers had no closed system of alliances and conflicts. Instead, they participated in many European alliances and for a century almost every combination involving the two Nordic powers and the five European Great Powers, France, Great Britain, Russia, Prussia and Austria, was tried. Behind these changes it is, however, easy to discern a certain continuity. Russia and Denmark were on guard against Swedish attempts to regain a strong power position in the Baltic, and Sweden up to 1789 normally had friendly relations with France. Versailles saw the Nordic country as a useful part of various political combinations and alliances, a valuable source of naval stores and an unlikely enemy.
The first years of peace after 1721 were uneasy in the Baltic. Russia wished to assert its new power by putting pressure on both Sweden and Denmark-Norway and the Russians used their growing navy primarily as an instrument of that policy. Up to 1727, England repeatedly sent fleets to the Baltic as a counterweight to Russia. After that the Russian Navy rapidly declined as conservative Russians tried to eliminate many of Peter I’s reforms. In the 1730s, France and Sweden gradually became closer and discussed possible actions against Russia; either a Swedish attack in the Gulf of Finland, or (as in 1734) a Swedish intervention in Danzig in support of French policy during the War of the Polish Succession. After the Russian defeat of Sweden in the war of 1741-43, a period of high tension followed in the Baltic until 1751. From time to time, war seemed imminent between various combinations: Russia and Sweden against Denmark (1743-44); Sweden against Denmark and Russia (1746-47); Prussia and Sweden (supported by France) against Russia and possibly Denmark (1748-49). After some years of lower tension, Russia and Sweden found each other as allies in the great coalition against Prussia in 1757-62, although both states avoided war with Prussia’s ally, Great Britain.
The 1760s was calmer in the Baltic but it became increasingly obvious that the three Great Powers which had emerged in eastern and central Europe: Russia, Austria and Prussia were bent on territorial expansion. They had, however, learnt to cooperate rather than to fight each other and the chief victims of this new policy were Poland and the Ottoman Empire. For the Baltic, the repeated divisions of Poland (1772-95) and the Russian-Austrian plans to divide the Balkans had the important naval consequence that Russia increased its sailing battle-fleet from that of a second-rank regional power to that of a European great sea power. The navy was intended both for deployment to the Mediterranean during wars with the Ottomans and as a protection against possible Western interference in Russia’s Polish strategy. Another consequence was that the secondary powers in the Baltic began to feel both under threat and a desire to take part in the great realignment of European powers. One example of this was the agreement of 1769 between Russia, Prussia and Denmark to make a joint military intervention against Sweden if the king strengthened his domestic political power.
King Gustav III (reigned 1771-92) of Sweden did in fact strengthen his power by a coup in 1772. This caused an international crisis but the three neighbours failed to act effectively. France supported Gustav, the Danish court was involved in a crisis, Russia was at war with the Ottomans and a large part of the Baltic battle fleet was in the Mediterranean. Technically, the large Prussian Army might have invaded Sweden, supported by a combined Danish-Russian fleet (if France had not sent a fleet to the Baltic), but in fact not even a naval demonstration was attempted. Alliances had shown their weakness and Gustav III had got an appetite for coups which might create faits accomplis. By 1779-80, he had begun to prepare for a conquest of Norway by a surprise naval attack on Copenhagen. When Russia failed to agree to his plans of mutilating the Danish Kingdom, he attacked Russia instead, in the hope that his expanded navy would give him a technological advantage.
The long period of war from 1792 to 1815 saw a dramatic realignment of borders and power structures in the Baltic. Denmark-Norway became involved in conflicts with Great Britain, which saw the large Danish-Norwegian Navy as a threat to the European balance of naval power. The navy was captured and the Danish government lost control of the lines of communication within the monarchy. Sweden lost Finland to Russia and attempted to compensate for that with a conquest of Norway. Even more so than earlier, the sea became the `natural’ border between the Nordic countries.
At the beginning of the eighteenth century, the Baltic had been dominated by two states which by geography tended to be maritime, Sweden and Denmark-Norway. Both had very large navies (and armies) in comparison with their small population base. Russia’s determined effort to become a European Great Power and a major sea power had changed Baltic power politics considerably, but up to the 1780s the three Baltic powers could participate in European power politics as sea powers of the same order. In all the wars and alliances which have been briefly mentioned in this section, warfare in the Baltic was oriented around maritime lines of communication that would give the navies a decisive role. Naturally, this was an advantage for the two Nordic powers with their smaller population base but relatively strong navies. The Danish-Norwegian sailing battle fleet was normally the largest of the three, but Russia and Sweden also had large oared flotillas for amphibious warfare.
By 1800, the Baltic had become an area of contest or cooperation between Great Britain and Russia. By 1815, they were the two European superpowers whose maritime and continental interests were to determine much of nineteenth-century world politics. The smaller Baltic powers, now far from domination, had to use the sea as a barrier against invasions from the Great Powers in east, west and south. Technical development in the nineteenth century would gradually make it possible to formulate new naval doctrines where purely defensive naval forces could provide credible coast defence systems against Great Powers. But the days when the Nordic powers could use their battle fleets as parts of the European balance of power and as instruments of offensive warfare had gone.