From: Rob Fowler <fowler@cs.rochester.edu>
Subject: Re: Secret Weapons Flops Flops
Organization: University of Rochester
Date: Wed, 30 Dec 1992 15:24:36 GMT


From Rob Fowler <fowler@cs.rochester.edu>

In article <Bzs8vA.LK7@law7.DaytonOH.NCR.COM> Brian Douglass
<anasaz!briand@anasazi.com> writes:
>
>As to counterbattery, while allied searches searched extensively for the
>weapons, they never could find them.  And eventually their own wear put
>them out of action.
>
Uhhhh...  While I haven't looked at it in a few years, H.W Miller's
"The Paris gun; the bombardment of Paris by the German long range
guns" (1930) indicated that counterbattery action was 
effective against these guns;  their sheer size and
immobility was one of their great flaws since  it required 
weeks to construct emplacements and move the guns between
emplacements.  Furthermore, since the Paris guns were intended
to attack a target well behind the front, they had to be
placed near the front within range of smaller, cheaper, and
more mobile French artillery.  

My recollection of Miller's account is that:

(1) At first the French thought that the first annoying explosions
were aerial bombs dropped from a silent, high-altitude plane.  From
the timing, dispersion, and shell fragments, the French quickly
figured out they were dealing with long-range artillery. 

(2) From the dispersion of shots they figured out the general location
of the battery.  The dispersion was in a very long, skinny elipse
since the very high barrel wear made each shot unique and range varied
wildly from shot to shot.  Since the Germans didn't have any forward
spotters (Flying an observation plane over Paris was a suicide
mission.  The Germans relied on accounts in Swiss newspapers for their
long-term spotting.), the guns had built-in crusher guages to measure
peak pressure in order to guesstimate where the last shot landed.  The
on-site Krupp engineers computed the powder charge for each shot using
the last shot's peak pressure and the headspace of the currently
loaded shell.  This didn't help the rate of fire. 

(3) From old (weeks or months) aerial photos (reproduced in Miller),
the French found railroad spur lines leading to the gun emplacements,
but initially misguessed just how far the tracks went for some of the
emplacements.  The Germans concentrated their air cover to prevent aerial
observation while the guns were in operation.

(4) Although the Germans tried to hide the Paris guns by firing other
batteries at the same time, the distinctive sound of the Paris guns
allowed acoustic location devices to successfully narrow in on the
location of the batteries. 

The Paris guns were only a few (6-8) miles from the Front, so within a
few days the French brought in a couple of batteries of railway
artillery in the 8" to 12" range and started bombarding the suspected
emplacements along the railroad spurs.  While they didn't score any
direct hits on the monster guns, they did inflict casualties, and
they did force the crews to spend large parts of their lives in deep
bunkers rather than doing their jobs. 

One of the guns in the initial set of emplacements was destroyed,
killing a large number of crew.  At first the Germans thought the
explosion was one of the French 12" shells that had been harassing
them, but it turns out the gun blew up its own breech.  Because of the
high velocity, a major technical problem was engineering explosive
shells that could take the forces of acceleration in a rifled barrel.
Miller's book has a plate of various unsuccessful shell designs.  One
of the problems was that conventional soft (e.g. copper) driving bands
were shredded by the rifling of the barrel, so Krupp wound up
machining driving lugs into the hardened steel body of the shells.
(This probably accelerated barrel wear.) My recollection of Miller's
best guess as to what happened was that somehow a shell was improperly
loaded: out of sequence, or not engaging the rifling properly, or
rammed with insufficient force so it backed out of the rifling when
the gun was elevated.  Anyway, a combination of the harassing
counterbattery fire and the failure of this gun caused the Germans to
dismantle the guns and relocate them some time later at another part
of the front where they were even less effective. 

Rob Fowler
fowler@cs.rochester.edu

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