The Norwegians, however, ignored the treaty and declared their independence. In response, the Swedish king, Karl XIII launched a military campaign in the summer of 1814. The short war ended with the Convention of Moss, a ceasefire and negotiated settlement by which the Norwegian government accepted a loose personal union with Sweden. Norway became a relatively autonomous constitutional monarchy with Karl as king.
By the end of the nineteenth century the union began to show signs of strains. The protectionist measures adopted by the Swedish government affected the Norwegian economy, which was more dependent on foreign trade. Tensions escalated when a succession of Norwegian governments demanded that they be allowed to send their own consuls aboard rather than rely on those appointed by the Swedish foreign minister.
King Oscar II dismissed the Norwegian demands, declaring that such a measure would erode his right to decide on foreign policy. As a consequence of royal intransigence the Norwegian Conservative politicians joined their Liberal counterparts who had long insisted on greater autonomy for their country. In 1905 the Liberal politician and shipping magnate formed a coalition government with the Conservatives. The government had one goal, to enact legislation in the Norwegian parliament (called the Storting) to allow them to appoint their own consuls.
When the king vetoed the legislation the entire government resigned in protest. Oscar declared that he was unable to form a government under those circumstances and in response on 7th June 1905, the Storting unanimously declared that the union with Sweden to be effectively dissolved. In an address they stated,
Whereas all the members of the Cabinet have to-day, in the Storthing, resigned their posts, and whereas Your Majesty in the Protocol of May 27 officially declared that Your Majesty did not see your way clear to create a new Government for the country, the Constitutional Regal power in Norway has thereby become inoperative.
It has therefore been the duty of the Storthing, as the representative of the Norwegian people, without delay to empower the members of the resigning Cabinet to exercise until further notice as the Norwegian Government the power appertaining to the King in accordance with the Constitution of the Kingdom of Norway and the existing laws with the changes which are necessitated by the fact that the union with Sweden, which provides that there shall be a common King, is dissolved in consequence of the fact that the King has ceased to act as King of Norway.
Initially, the Swedish government decried the declaration as an act of rebellion; however, they were open to a negotiated settlement but they demanded that the Norwegian people be asked to decide the future of their state.
The results of the plebiscite held on 13th August gave a ringing endorsement of the Storting’s decision, with 99.95% of voters in favour of dissolution. Negotiations between the Swedes and Norwegians began at the end of that month. While some Swedish politicians preferred a hard-line response, the king decided that an end to the union was preferable to war between the two countries. In October both parliaments ratified the terms of the dissolution, with Sweden formally recognising Norwegian independence on the 26th October when Oscar II renounced his and his descendents’ claim on the Norwegian throne.
Project Gutenberg hosts an e-text of Karl Nordlund’s The Swedish-Norwegian Union Crisis, in which you will find many primary source texts related to the dissolution.