Welcome to the forum, Alfred, and thanks for your PM. The flag can be read and understood like this -
久長運武 (= 武運長久) Continued luck in the fortunes of war
祢宜町五丁目 Negi-cho 5-chome (address near Nagoya City)
少年日參團 Shrine Boy Scout
(Seal on the right-bottom)
武運長久 熱田神宮
Continued luck in the fortunes of war by Atsuta Shrine (in Nagoya City)
This flag was manufactured by parents of a shrine boy scout to sell as a souvenir at Atsuta Shrine in the postwar.
A very good authorized flag by a famous shrine.
Hope this helps.