A map of Sweden's territorial gains and losses 1560–1815. In the years that Vasa
was built and sank, Sweden still had not seized the southernmost of its present provinces, but possessed almost all of modern-day Finland
as well as Ingria
During the 17th century, Sweden went from being a sparsely populated, poor, and peripheral northern European kingdom of little influence to one of the major powers in continental politics. Between 1611 and 1718 it was the dominant power in the Baltic, eventually gaining territory that encompassed the Baltic on all sides. This rise to prominence in international affairs and increase in military prowess, called stormaktstiden ('age of greatness' or 'great power period'), was made possible by a succession of able monarchs and the establishment of a powerful centralised government, supporting a highly efficient military organization. Swedish historians have described this as one of the more extreme examples of an early modern state using almost all of its available resources to wage war; the small northern kingdom transformed itself into a fiscal-military state and one of the most militarised states in history.
Gustavus Adolphus (1594–1632) has been considered one of the most successful Swedish kings in terms of success in warfare. When Vasa was built, he had been in power for more than a decade. Sweden was embroiled in a war with Poland-Lithuania, and looked apprehensively at the development of the Thirty Years' War in present-day Germany. The war had been raging since 1618 and from a Protestant perspective it was not successful. The king's plans for a Polish campaign and for securing Sweden's interests required a strong naval presence in the Baltic.
The navy suffered several severe setbacks during the 1620s. In 1625, a squadron cruising in the Bay of Riga was caught in a storm and ten ships ran aground and were wrecked. In the Battle of Oliwa in 1627, a Swedish squadron was outmaneuvered and defeated by a Polish force and two large ships were lost. Tigern ('The Tiger'), which was the Swedish admiral's flagship, was captured by the Poles, and Solen ('The Sun') was blown up by her own crew when she was boarded and near capture. In 1628, three more large ships were lost in less than a month; Admiral Klas Fleming's flagship Kristina was wrecked in a storm in the Gulf of Danzig, Riksnyckeln ('Key of the Realm') ran aground at Viksten in the southern archipelago of Stockholm and Vasa foundered on her maiden voyage. Gustavus Adolphus was engaged in naval warfare on several fronts, which further exacerbated the difficulties of the navy. In addition to battling the Polish navy, the Swedes were indirectly threatened by Imperial forces that had invaded Jutland. The Swedish king had little sympathy for the Danish king, Christian IV, and Denmark and Sweden had been bitter enemies for well over a century. However, Sweden feared a Catholic conquest of Copenhagen and Zealand. This would have granted the Catholic powers control over the strategic passages between the Baltic Sea and the North Sea, which would be disastrous for Swedish interests. As it turned out, the Imperial occupation of Denmark ended before Swedish intervention was necessary, and a squadron assigned to assist Denmark was retasked to help lift the Imperial siege of Stralsund.
Until the early 17th century, the Swedish navy was composed primarily of small to medium-sized ships with a single gundeck, normally armed with 12-pounder and smaller cannons; these ships were cheaper than larger ships and were well-suited for escort and patrol. They also suited the prevailing tactical thinking within the navy, which emphasised boarding as the decisive moment in a naval battle rather than gunnery. The king, who was a keen artillerist, saw the potential of ships as gun platforms, and large, heavily armed ships made a more dramatic statement in the political theater of naval power. Beginning with Vasa, he ordered a series of ships with two full gundecks, outfitted with much heavier guns. Five such ships were built after Vasa (Äpplet, Kronan, Scepter and Göta Ark) before the Privy Council cancelled the orders for the others after the king's death in 1632. These ships, especially Kronan and Scepter, were much more successful and served as flagships in the Swedish navy until the 1660s. The second of the so-called regalskepp (usually translated as 'royal ships'), Äpplet ('The Apple'; the Swedish term for the globus cruciger), was built simultaneously with Vasa. The only significant difference between the design of Vasa and her sister ship was an increase in width of about a metre (3.1 ft).