Thread by @less_soft_bird

you ever just develop a new hyperfixation out of nowhere?
🧵🧵🧵
Today l visited a local airbase museum, which was a German airfield in WWII and the largest in the country, at the time.
Nearby was a Luftwaffe (Lw) command center in a huge bunker, which l didn't know.

The bunker itself, codenamed DIOGENES, is a 40x60x16 meter(!) concrete block with walls between 3 and 4 metres thick. From there, the Lw. controlled the entire airspace of the Netherlands and Belgium. The RAF somehow completely missed it, despite its size.

In this bunker, they also kept track of enemy planes using data from nearby radar stations, and that tracking was the thing that caught my interest.

After talking to the museum guide for about four hours- he's in his 80s and experienced the war in person- and pretty much being a sponge for the guide who was infodumping at an incredible rate, he wanted to show me something they've found inside DIOGENES.

The Germans used a tracking room, divided in two by a giant glass screen with an engraved map. Officers were seated on one side, deciding how to respond to enemy bombers. On the other side, 75 women armed with small flashlights shone lights on the map to represent enemy aircraft.

They also used other, smalled glass maps to plot out weather info and flight paths.

The museum guide told me they'd found one of these smaller maps and that they were reconstructing it. It wasn't yet part of the exhibit but he wanted to show me, one nerd to another.

When the Nazis lost the war, they destroyed the interior of the bunker by detonating bombs inside. The bunker itself survived, though the interior was lost.
Someone saved the shards of one of the maps though!

Yeah, it's a huge map, with a ton of tiiiiiiny shards of glass. A fun history jigsaw, but a lot of pieces are missing & we don't know how many there are anyway.
Engraved in its surface are gridlines, rivers, city names. Surely we can use that to put it back together, right?

That's not just what they did here though. Glass was made fairly flat in the 40s, but nowhere near as flat as we do today. There are minute differences in the thickness of the glass, especially on large panes like these.
You can measure & map that to figure out where pieces go!

So they've measured big chunks with known locations to determine where unmarked smaller pieces might belong. As you can see here, differences are small (in micrometers!) but enough to differentiate with.

And it seems to work just fine! They've been doing this for a long time now, and they're making good progress. Awesome!

But the part that intrigues me most? DIOGENES is virtually unknown over here. I know a fair bit about local wartime history and didn't know it was there.

It's huge! Now that l know where it is, it's hard to miss. And that it was basically the local Luftwaffe HQ which employed over 600 people? l had no idea. And at least you can still find this info online with a bit of effort.

The glass maps though? There's next to nothing.

Nothing in this country even mentions that one of the DIOGENES maps has been found and is being restored. There's no info on it, (except this thread now, l guess).

After *hours* of looking l found a low-res photo of what appears to be an intact version of this map. Neat.

For a region with such a vivid WWII memory (Market Garden happened here! Chunk of the bridge shown below), it's weird to me that this concrete block is just sitting there, hiding in plain sight.

And especially, it's weird to me that this map just exists and nobody knows about it. Early radar tracking, air defense, *huge* bunker with hundreds of people involved, cool Nazi tech, and there's just no info at all.
You just hit a concrete wall when looking it up.

So, l want to ask the museum if they need any more volunteers with the glass jigsaw puzzle; it seems like something l'd enjoy doing, along with hours spent looking through obscure resources in 3 languages to find more info on the technology. They're open tomorrow, so l'll go ask!

l'm not big on military things, but to me this just feels like a mystery that needs to be solved. It's not a big secret important discovery, but it sure is Tom Scott-level interesting history.

Anyway, here's the surprisingly intact turbine blades of a crashed Messerschmitt Me262 (first jet engine plane!) that's spent 70 years embedded in the soil.

And some other crashed plane parts; all surprisingly intact given their age and the conditions they were found in! (gotta go back with a decent camera sometime)

anyway l've lived here for years and drive past this museum multiple times a week, decided to check it out because why not.
Totally wasn't aware they had a huge collection of Really Cool Things, especially for a tiny local museum in a town with more horses than human residents.

German = Nazi German of course, bit of a Dunglish fuckup there

hey @tomscott you should do a video about this obscure WW2 nazi germany radar map tool thing

oh and here's a spinoff thread on finding invisible bomb craters using height maps

https://twitter.com/less_soft_bird/status/1571273581845176323?t=EAtFdj9qEjN1oQLxFbUYag&s=19

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