Sweden did indeed honor its promise and sent a warship. Frederick VII "rightfully" leapt aboard.
The reason Sweden was so enthusiastic about helping Denmark was not that the two nations had a particularly good relationship. On the contrary, as mentioned before, they could be considered hereditary enemies.
It was simply that Sweden had been the victorious side.
Later generations knew only of such almost demonized terms as Pan-Germanism and Greater Slavism, yet they did not know that Sweden had its own Greater Scandinavianism.
Sweden might not have had much of a presence in later times, but in the nineteenth century, Sweden's political elite certainly did not see things that way. They had always regarded themselves as the true overlords of Northern Europe.
To contend for supremacy and consolidate its own position, Sweden had to unite Denmark and Norway. At the very least, it needed to establish a close military alliance so they could advance and retreat together.
There was also a more practical reason. Because the House of Bernadotte ruling Sweden had ties to Napoleon, its legitimacy was extremely weak.
Meanwhile, Danish King Frederick VII had no legitimate heirs. Yet he clung stubbornly to power and refused for the longest time to name a successor.
Swedish King Oscar I saw an opportunity to kill two birds with one stone. If he could obtain the right of succession from Frederick VII, Sweden could not only unify all of Scandinavia, but also resolve the issue of royal legitimacy in one stroke.
To onlookers, Frederick VII might have seemed like a capricious madman fond of making grand boasts, but he was still a king, and there were people willing to believe his words.
Oscar I, for instance.
Compared with taking part in ground combat, the Swedish generals who had been dispatched naturally preferred