This is a very short text on the matter and a lot of detail have been left out (a possible official version would fix that 
) - also, from 1870, the Scandinavian history is just fiction------------------------------------------------------------------------------------
How we got here
Up until 1814, Denmark and Norway had been in a Union (from 1660-1814), simply called Denmark-Norway. But under the Napoleonic wars, Denmark had allied herself with the forces of Napoleon, and when he was defeated - Norway was promised to Sweden by Great Britain, Russia, Prussia and Austria - since Sweden had been part of the allied forces against Napoleon and as a compensation for Sweden's loss against Finland in 1809, all under the treaty of Kiel.
Already in Norway, the viceroy of Norway, Hereditary Prince Christian Frederik resolved to preserve the integrity of the country, and if possible the union with Denmark, by taking the lead in a Norwegian insurrection. The king was informed of these plans in a secret letter of December 1813 and probably went along with them. But on the face of it, he adhered to the conditions of the Kiel Treaty by ordering Christian Frederik to surrender the border fortresses and return to Denmark. But Christian Frederik kept the contents of the letter to himself, ordering his troops to hold the fortresses. He decided to claim the throne of Norway as rightful heir, and to set up an independent government with himself at the head. On 30 January, he consulted several prominent Norwegian advisors, arguing that king Frederick had no legal right to relinquish his inheritance, asserting that he was the rightful king of Norway, and that Norway had a right to self-determination. His impromptu council agreed with him, setting the stage for an independence movement.
On 2 February the Norwegian public received the news that their country had been ceded to the king of Sweden. It caused a general indignation among most people, who disliked the idea of being subjected to Swedish rule, and enthusiastically endorsed the idea of national independence. The Swedish crown prince Bernadotte responded by threatening to send an army to occupy Norway, and to uphold the grain embargo, unless the country voluntarily complied with the provisions of the Kiel Treaty. In that case, he would call a constitutional convention. But for the time being, he was occupied with the concluding battles on the Continent, giving the Norwegians time to develop their plans.
Also in 1814, on the 17th of May, Norway had finished its constitution in Eidsvoll.
All the while through the decades, buildup of insurrection and the threat of war was brewing and on the 26 of July, a small war between Norway and Sweden erupted when a Swedish fleet took over Hvaler and 65000 Swedish troops invaded Norway and advanced North on the fortified city of Fredrikstad bypassing the fortress of Fredriksten. The Norwegian army retreated over the river Glomma, and the Swedish army tried to intercept them but were defeated at the battle of Langnes - a very important and tactical victory for the Norwegians.
A few days later on the 14th of August, a convention in the city of Moss was concluded, a general cease-fire based on terms that effectively were terms of peace.
Christian Frederik succeeded in excluding from the text any indication that Norway had recognized the Treaty of Kiel, and Sweden accepted that it was not to be considered a premise of the future union between the two states. Understanding the advantage of avoiding a costly war, and of letting Norway enter into a union voluntarily instead of being annexed as a conquered territory, Bernadotte offered favorable peace terms. He promised to recognize the Norwegian Constitution, with only those amendments that were necessary to open up for a union of the two countries. Christian Frederik agreed to call an extraordinary session of the Storting in September or October. He would then have to transfer his powers to the elected representatives of the people, who would negotiate the terms of the union with Sweden, and finally relinquish all claims to the Norwegian throne and leave the country.
This Union would be an uneasy one for the coming decades.
But when the 1870s arrived and the first Aether flyer by Edison were made, and the discovery of Mars and its liftwood came around. The Swedish-Norwegian Union could see that their overall hostilities toward each other had to end, a new era had begun and only the ones who could capture the momentum of the moment would come out on top or as equals.
The problem was that the Swedish might of arms, even with the Norwegian forces were not as it were before, and especially not after Sweden had expended so much effort in conquering Finland from Russia in 1875.
19th of August, in Göteborgh in Sweden - a secret meeting was held between Frederik Stang the Prime Minister of Norway and Oscar II King of Sweden; discussing a potential real alliance between the nations, a Union between nations and not only in the name.
After two weeks of discussions on how the Union could compete with the now emerging Space powers, it were concluded that the Union in it self would not be enough. So an emissary were sent to Denmark, and a month later a new meeting was now held in the Capital of Sweden, Stockholm, with Christian IX the King of Denmark. and on the 30th of September the Scandinavian Union was created.
In 1882, the first Aether fliers of the union touched upon Mars and a small colony were settled, another minor colony were also established on Venus in 1887, but only after a small Space battle between the Union and Belgian forces over a misunderstanding - this would lead to an open animosity between the two powers until this date.
A mission to Mercury is planned for January 1890.
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