Most of the defences were ready when the Great Northern War started. First in the year 1700 where the Swedes quickly dismissed Denmark-Norway, and then from 1709 onwards. The country lost many people, resources and areas around the Baltic Sea, after the Swedes success turned in 1709. King Charles XII mounted two desperate attacks on Norway in an attempted to win back resources and ensure a position to negotiate if Swedish mainland should be invaded.
First invasion came in March 1716. The invasion was aimed at Christiania (Oslo) and thus somewhat north of Fredriksten. The city was captured but Akershus fortress stood fast. As a result, King Charles XII could not get supplies by sea and this was a prerequisite for the continuation of the campaign, and he had to give up.
In May he manoeuvred his forces southwards to the border just outside Fredrikshald (Halden). Charles XII decided that he would attempt to take Fredriksten, which he had bypassed a few months earlier. This was no easy task, especially without heavy artillery. But after a few months of reconnaissance he found a “weak point” in the fortifications. It was not actually about the fortifications themselves, but that fact that the fortress did not have barracks to accommodate the entire garrison. A large contingency of the soldiers was housed in the town. Charles XII thought this obvious weakness should be exploited by attacking at night, preferably in heavy fog. By quickly attacking the Citizens fortifications, the fortress and the soldiers housed in the town would in effect be separated, and after that it would be a simpler task to take the fortress. This plan was put into action on the night of 4th of July. This is what is portrayed in this sequence.