Here a group of around 90 Norwegian soldiers fought against advancing German forces on 13 April 1940. It was a short-lived battle – the fort, which only had ‘reserve’ status, was not properly equipped, and they ran out of ammunition after just two hours of fighting. Today you can walk into the shooting gallery, a deep, cool corridor running along the side of the fort to the east, from which the soldiers fired against the enemy. The fort, which is located on a hill between Fredrikstad and Sarpsborg along Rv109, affords great views of the area, with the two arms of the Glomma river coming together just south of Greåker and the Rolvsøy bridge. It is particularly pretty in early autumn, when all the deciduous trees in the area change colour and paint the landscape in shades of orange and golds. The fort, which was built in the early 1900s, was listed in 2000.