Hordaland had been steadily increasing its control over the Isles since the time of Magnus III. Orkney had firmly become a Hordalandic possession in the 12th century, the Faroes in 1499 and Man was by this time all but a vassal. Iceland seemed the next obvious step, especially as Hordaland's king, Olaf VII, increasingly saw Leifia and its trade routes as a potential cash cow. Iceland had previously happily traded on its neutrality as a small and niche mercantile country, much like Lade. The Danish takeover of Lade and its modest trade routes had removed Iceland's only real ally and isolated it diplomatically from Europe (which rarely gave it much thought as it was). Therefore Olaf VII thought absorbing it into his realm would be an easy operation. Iceland operated a mercenary army, at that time deep in the ongoing bloodbath in Italia, and had a small merchant navy. But compared to the numbers Olaf VII could command he figured there would be little resistance at all. He did not reckon with Vinland's intervention.
Iceland had of course 'given birth' to Vinland in the 11th century but Vinland had comfortably outgrown its parent in the interim, both in terms of wealth and population. Still, most Vinlanders would have recognised Iceland as the 'mother country' and there was considerable deference to Icelandic merchants over other nations. Their languages were still virtually indistinguishable and there was a steady if not huge movement of peoples between the two, increasing in the years when famine or volcanoes spelled disaster for Iceland. Vinland had happily taken over Greenland in 1353, reducing a previously precarious but persistent colony to a mere earldom within Vinland. Some in Iceland worried they would be next but Vinland's Althing and crown made no overt moves at domination. Iceland's assistance, though small, was much appreciated by the Althing during the Vinlandic Civil War and Great Northern Wars and most senior politicians had come to regard the island as a partner rather than a potential subject territory. In fact it was more worried about Hordaland's moves than making any of its own. Reports that Hordaland had threatened Iceland shook the Althing into action. The question whether 'if Iceland fell would Greenland be next?' soon had the chamber united.
In March 1510 Olaf's emissaries delivered a simple message to the Icelandic Commonwealth; accept vassal status within the Hordalandic realm or face the consequences. The demand had been hinted at the previous summer and came as no surprise. As soon as the emissaries were dismissed Iceland sent its own diplomats westward to Isafjordhur.
United, the Althing voted an extra skat for the year allowing the crown to raise an army out of the usual Eikland militias and Suderfolk irregulars, mostly Wampanoag, too. Transport ships were requisitioned and a substantial store of food gathered to help feed the army in notoriously famine prone Iceland. With preparations complete the fleet set sail in May. Hordaland had already begun its blockade by the time the Vinlanders arrived and most of the fleet decided to retreat to Greenland to avoid being detected and engaged. The cargo ships carrying food slipped past the patrols however, using a fog bank to evade capture. Although the food was only a small amount compared to what Iceland needed to continue through the blockade it boosted morale of the defenders and angered Olaf VII considerably when he found out.
Hordalandic forces were soon sent to occupy Reykjavik, the largest town of Iceland and all but unfortified, but the Vinlanders had already landed its Suderfolk levies and the invaders were repulsed in a scrappy fight. By the end of summer the Vinlandic irregulars had skillfully repelled several landing by Hordalandic forces along the south coast.
Eventually Olaf VII grudgingly abandoned the attempt. He had other more pressing matters to deal with in Ireland. Denmark too had woken up to the conflict as well and with its armies engaged in the War of Anglian Succession it issued a severe rebuke. If the Kalmar nations could not maintain a united front then how could they possibly resist the ambitions of the Luxembourgs?
Paying fealty to Christopher II in an embarrassing ceremony in Oslo, Olaf VII would redirect Hordaland's energies into the War of Anglian Succession, with its army quickly earning a reputation for daring and even foolhardy action.
Vinland would make a renewed attempt to help its ally; a dedicated Icelandic wharf was built as Fjallasay solely for the use of Icelandic merchants and a near-permanent ambassador was sent to Reykjavik to ensure a close working relationship. Relations with Hordaland meanwhile disintegrated and the two testily avoided each others' spheres. The 'northern route' across the Atlantic was decreasing in importance anyway. The direct routes to Mexica and the Taino Sea were becoming much more lucrative and Olaf VII's ploy in earning more money for Hordaland was perhaps outdated even before it began.
Iceland meanwhile took the view that without further expansion, financially speaking, of its own it would forever be at the mercy of Vinland and potentially predatory Scandinavian countries. It therefore began engaging with several Leifian tribes in the south east, beginning a process which would eventually lead to the annexation of Rolegurfolkland.