Norby commanded the largest ship of Hans' fleet during the war against Sweden and Lübeck from 1507 to 1512, and served alongside Jens Holgersen Ulfstand.

[1] He captured, and was subsequently granted, Borgholm on Öland in 1519,[3] and his blockade of Stockholm helped Christian II secure the Swedish throne in 1520.

[3] Norby was tasked with finding a sea route to the West Indies via Greenland, but had to abandon his plans due to the rise of Gustav Vasa who was crowned King of Sweden in 1521.

He was isolated and began minting his own coins in order to pay his men, bearing the name insignia Severin Norbi.

After diplomatic machinations, Norby eventually stayed at Visborg, and he launched a rebellion in Blekinge in April 1525,[3] in the name of Christian II.

During the surrender of Visborg, Norby was double crossed by Frederick I's advisor Otte Krumpen and left for capture by Lübeck.

[2] Kragh Nielsen, Niels H., "Søren Norby : en handlingens mand på Christian 2.s tid", Statens Forsvarshistoriske Museum, 2010 ISBN 978-87-89022-62-8