In 1436 another rebel army marched on the castle, this time led by the Marshal of the Realm, Karl Knutsson (Bonde), who persuaded the German castellan Mattias van Kaalen to surrender Älvsborg without a fight.

Älvsborg was subsequently besieged twice by Norwegian forces, in 1452 and 1455, but was successfully defended by Tord Bonde, King Karl's cousin.

It was subsequently rebuilt by the Swedes, only to be captured again in 1519, and this time the Danes held onto it for four years, until the end of the Swedish War of Liberation.

[7] Älvsborg was strengthened and modernised by King Gustav I, transforming it from a mediaeval castle into a Renaissance fortress with up-to-date trace italienne outworks.

[13] The repeated capture of Älvsborg by the Danes demonstrated that the fortress was no longer defensible, in large part because the improved range and power of modern gunpowder artillery meant that it had become chronically vulnerable to bombardment from the adjacent Sjöbergen [sv] hills.

Accordingly, in 1650 Johan Wärnschiöldh [sv], the Quartermaster-General of the Swedish Army, proposed that Old Älvsborg be demolished in order to render it useless to any invading forces.

[15][16] Those parts of the castle ruins which were not destroyed by the construction of the factory can still be seen today on the summit of Klippan, although a canopy has had to be erected to protect them from further damage.