While bombing a man-made mountain of useless mine debris wouldn't appear to be an earth-shaking development,
just the fact that Germany could project air power so far from home - and so far inland - could serve to demoralize a wartime populace. (Which is why the locals apparently were told to keep quiet about it.) Powered flight and aviation were barely a dozen years old at the time - making this daring raid even more spectacular.
In July, 1998, I happened to mention the subject on the rec.aviation.military newsgroup, asking if anyone had information about Zeppelin raids on Scotland in 1915. Graham Salt, a British writer, historian, and aviation enthusiast was among a number of people who responded. Yes, he said, Zeppelins had bombed London during the summer of that year, and by September of 1915, a squadron of the huge airships had attacked Manchester, far to the North, as well as industrial sites in the northern parts of England, near the border of Scotland. Unfortunately, the flight logs for two of the craft were lost when they ditched at sea, returning to Germany. There was speculation that these two had gotten lost in bad weather, and had cruised on into Scotland a bit - but these facts had never been independently confirmed.
Then I told my mother's story to the group - and I am still getting an occasional email from a researcher, wanting to "interview the lady who remembers the Zeppelin raids in Scotland".
They are disappointed when I tell them she died in 1986, or that she was only five years old at the time, and could hardly be expected to provide dates and times or a description of the engine noises or bomb explosions. However, her recounting of a childhood memory to her son has added just a little bit of clarity to the lost traces of time and history, 83 years after the fact.
You never know how a seemingly-insignificant thing can eventually improve historical records.
By the way - Count Zeppelin's huge machines are STILL the largest aircraft to ever have flown, dwarfing the "Spruce Goose" of Howard Hughes, the 747, the C-5, and even that enormous Russian behemoth, the six-engined AN-226. (Their "Black Sea Monster" sea- skimming ground-effect vehicle is larger - about the size of a battleship - but the experts are unsure whether or not to call it "flight".)