Mamula is situated on the island of Lastavica which means Swallows after the birds that are often seen wheeling overhead.
After the first world war when the empire was overthrown, Mamula continued to have a life as part of the historic culture of Montenegro. In World War II, it was used as a prison by the Italian invaders. Every year, the release of prisoners is commemorated in Montenegro on 14th September. This cache was placed to mark the anniversary.
The island must be visited by boat, and if you do not have your own, one of the best ways is to drive to the lovely fishermen's village of Rose on the Luštica peninsular. From there, it is possible to hire a boat to the island from the Konoba Adriatic, a waterfront cafe covered in vines and other exotic plants. You will need a minimum of 1 hour to explore the fortress and find the cache, assuming that the island has not been taken over by developers or made private. As you travel along the coast towards the island, you will pass an old submarine pen set in the rocky shoreline. Drawing nearer to Mamula, look out on the opposite shores to see two other fortresses of Arza and Ostro. When you return to Rose, you will probably want to take a rest and a meal after your trip.
If you want to learn more about these fortresses, check out "The Austro-Hungarian Fortresses of Montenegro - A Hikers Guide" This is available from Amazon Books, "So Bookstore" in Herceg Novi or the "Forza Souvenir Shop" by the main gate in Kotor.
If you already have a copy, please post a photo holding it near the fortress!