Milo NN was created in 1966 along with five other military areas as part of a reorganisation of the administrative divisions of the Swedish Armed Forces. It can be seen as the successor of II. militärområdet (II. Military Area) created in 1942, but that did not have the same tasks as Milo NN. The military area consisted of the land covered by the above mentioned counties, and from 1982, also the southern part of Gävleborg County. In 1993, the number of military areas of Sweden was decreased to three, and as a consequence of that, Milo NN was merged with Milo ÖN to create a new military area, Milo N.