This series of drawings, published in the Illustrated London News 22 January 1938 (available hrough our blog bookstore), by the incredibly prolific and detail-oriented G.H. Davies depicts one segment of the city defense program being formulated by the British government in the last year or so leading up to the beginning of the European end of World War Two. (I own 150 or so of these images by Davies--he never fails to provide the detail where you need it.) The overall plan for defending major British cities consisted of anti-aircraft guns, searchlights, R.A.F. fighter squadrons and interceptors, and the "Balloon Barrage". London and suburbs are featured here, all to be protected by a series of ten squadrons of fifty balloons each, handled by a crew of ten. The thinking was that it would make low-level bombing by fighter aircraft impracticable, and force any aircraft attempting such an approach to a higher altitude where they would be theoretically susceptible to the interceptor squadrons.
I'm not terribly sure why the thinking was against low altitude attack, but my best guess is that the planners were thinking about the He-111Bs and Ju52s or other such aircraft that the Nazis checked and tested out against the Spanish Republicans during the Civil War. Perhaps freshest of all memories of the German operation Feuerzauber (Magic Fire) was the Guernica raid, just a year or so before the publication of these images, where that militarily insignificant town was attacked from the air in twenty minute intervals over three hours, destroying it in a terror blitz. If I was sitting around a big table at 10 Downing, I’d have that picture in my head. .
Be that as it may, the "air mine field" looks terribly inefficient and vulnerable to me, sort of like an exposed Maginot Defense Line, but without the very deep misunderstandings that went along with the highly questionable French effort.
Explanation of the Images:
a) The first image shows the incredible perimeter defense network, which extended ten miles around St. Paul’s; the balloons were moored at 100 yard intervals, making for 1100 or so balloons to “fence” the perimeter.
b) The second image shows London center and immediate suburbs, with another 500 balloons in a smaller circle inscribed in the larger.
c) The third image is a close-up of the balloons, looking down; seems as though they were tethered at about 2000 feet or so
d) The last image is a close-up of London center.