In my previous post I talked about some Japanese ARP posters from 1938. One in particular (above; click for larger version) is very revealing: it shows exactly whose bombers the Japanese were worried about, by plotting circles on a map of Japan and its neighbours, representing the radius of action1 of bombers from potential enemies. It turns out they were afraid of everybody's, except for the country they were actually at war with (China). The brown circle shows the radius of action of American bombers from the Philippines; black, British bombers from Hong Kong; green, Russian bombers from Vladivostok; yellow, American bombers from Alaska; and blue is in the middle of the ocean — American carrier-borne bombers, most likely. The circles are marked with a number, probably a distance: 2000 km? That would make some sense, as it was very roughly the radius of action of the B-17s that were just entering service in the US Army in 1938 (though not in substantial numbers until 1941).
This sort of map is quite common these days, particularly in highlighting the danger from rogue states. For example, here's one centred on North Korea, from a website criticising Clinton's foreign policy:
The circles here are not the radii of action of bombers, of course, but the ranges of missiles.2 But the principle is the same. There's a subtle difference, though: the Japanese one projects a defensive outlook: it shows the circles encroaching on Japanese territory and so emphasizes how vulnerable Japan is. The North Korean map, on the other, does not highlight the threat to any particular country, but instead demonstrates how North Korean missiles threaten all of its neighbours — that is to say, just how rogueish a state it is.
Here's another missile-era map, this time quite an historic one from the Cuban missile crisis in 1962 (looks like it was drawn up by the CIA). This is more like the Japanese map: though the threat is from Cuba, the centre of the map is shifted towards the United States, to show just how much of the country would fall under the shadow of Soviet missiles (but by the same token, de-emphasising the threat to South America).
I haven't come across many other pre-Second World War examples, though I'm sure they exist. The only other one I currently know of is British, and is very early, dating from 1913:
This time it's not bombers or missiles that are the threat, but Zeppelins. (Love that OTT title!) The map is centred on Heligoland, which another map in the same magazine claimed was the site of an airship station. The caption says that the outer circle (600 miles) represents the radius for Zeppelins; the 300 mile circle is for aeroplanes. It 'should bring home to every patriot the vital necessity of Britain putting her house in order forthwith, by the grant of adequate provision in the nation's Estimates to enable us to make up the heavy leeway from which this country already suffers'. Indeed it should; those circles are very dark, aren't they? Though that might just be the poor quality of my photocopy …
- No more than half the maximum range of an aircraft, assuming they return to the base from which they took off.
- As missiles don't return to base, their radius of action is equal to their range.
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