Apart from the forts, the garrison itself was heavily expanded during the initial construction years and became the largest garrison in Sweden, taking an exceptional position in Swedish military history of the 20th century; even at the start of the 21st century, Boden was the largest garrison city in the Swedish Army. Still, no other fortifications than the forts themselves were finished by 1908, and work now started to fill the holes in between them. It was realised that prepared positions were needed for the mobile batteries, and apart from those, three larger battery positions (sometimes called "fästen", strongholds) were also constructed at Leåkersberget, Norra Åberget and Svedjeberget. These works were started in 1911 and were finished during the First World War. The last of the three strongholds was positioned in the mountain itself with embrasures in the mountain side, and Leåkersberget had parts of the battery position inside the mountain, but the gun emplacements outside—the other positions were concrete fortifications above the ground, some inside a bunker and others behind a parapet.