File No.: Case File # 14
Nazi Hollow Charge Attack on Belgian Casemate
Subject: German airborne troops using hollow charge explosive ordnance in their attack on a Belgian Fortress during the Blitzkrieg.
Investigation made at:
Fort Eben Emaël, Municipality of Eben Emaël, Belgium
Period Covered:
May 10th & 11th, 1940
Date:  April-May 2010
Case Classification: Description of Nazi airborne forces attack on Belgian fortress during May 1940 invasion
Status of Case: Case Closed
Introduction: This Case File describes a small element of the assault on the Belgian fortress Eben Emaël in May 1940. Scores of publications have been written about this fortress and the overall assault on it, but we focus on a special weapon first put to use for military assault purposes.

REASON FOR INVESTIGATION:  In the period right after the attack and during the Nazi occupation of Belgium and other European countries, the German propaganda machine did exploit their successful raid on the fort,
but deliberately failed to mention the use of "new types of assault weapons". At Eben Emaël the assault glider and the hollow explosive charge got their baptism of fire. In this Case File we reveal to the general public the use of the hollow charge as a weapon kept secret to it by the Nazi's.

The Belgian fortress was constructed inside a hill with artillery casemates and armored cupolas on the hill's plateau and was considered impenetrable at the time it was built, between World War 1 and 2. On May 10th 1940 it was proven that the concept of national defense by means of gigantic chains of fortified artillery positions had become obsolete.
On that day well-trained German airborne assault troops used speed, the element of surprise and new military techniques to put the fortress's powerful artillery out of action in a very short amount of time. One of the aforementioned new military techniques was the assault glider; the other special weapon was the so-called hollow charge.

A hollow, or shaped, charge is a concave metal hemisphere or cone backed by a high explosive, all in a steel or aluminum casing.
When the high explosive is detonated, the metal liner is compressed and squeezed forward, forming a jet whose
tip may travel as fast as 10 kilometers per second.

Charles Edward Munroe was the inventor of "The Monroe Effect" in explosives in 1885. He noted that a high explosive with a cavity facing a target left an indentation. The Monroe Effect was rediscovered by Von Neumann in 1911, but no practical applications were developed. A Monroe-effect shaped-charge warhead can be expected to penetrate armor equal to 150-250% of the warhead.
                                   - source: -


The attack on the fortress was planned to start 5 minutes before the German "Blitzkrieg" invasion of the Netherlands and Belgium and was codenamed "Granit". Also three bridges across the Albert Canal were the objective of German glider borne troops.
They formed an 86 man unit, named "Sturmabteilung Koch", divided into eleven groups with varying missions.
The group of gliders assigned to attack the fortress was led by Lieutenant Rudolf Witzig.
These DFS 230 type gliders carried over 5000 lbs. of explosives. The attackers brought in flamethrowers and twenty-eight 50 kilogram hollow charges. Nine of the eleven gliders, attacking the fortress, landed on the hill’s plateau. Immediately after landing, each 8 men crew rushed from their glider and started attacking the three objectives most dangerous to them: the four anti-aircraft machineguns and the positions named MI NORD and MI SUD.
After eliminating these threats, the attackers focused on a casemate named "MAASTRICHT II"; a concrete bunker with three artillery pieces and a steel observation dome named "EBEN III". They threw a 12 and a half kilogram hollow charge into one of the canon holes and several hand grenades into the casemate’s ventilation shafts.
The steel observation dome was then put of action with a 50 kilogram hollow charge.
Of MAASTRICHT II's twenty four men crew only three artillery men escaped unharmed, six were killed and the rest wounded. In fifteen minutes the most important casemates, artillery cupolas, anti-aircraft positions and the machineguns in the bunkers were rendered "Kampfunfähig" (German: combat ineffective). In the following hours the rest of the fortress was attacked by entering the doorways to the tunnels and gun turrets.

This remarkable German victory was exploited in the Nazi war propaganda. The text of a German Wehrmacht communication dated May 11th 1940 put it like this:
"Das Fort wurde schon am 10. Mai durch eine ausgesuchte Abteilung der Luftwaffe unter Führung von Oberleutnant Witzig und unter Einsatz neuartiger Angriffsmittel kampfunfähig gemacht und die Besatzung niedergehalten."

(Already on the 10th of May the fortress was rendered combat ineffective and its crew captured by a selected Air Force unit under the command of Lieutenant Witzig deploying new types of assault weapons.)

To the public, these new types of assault weapons (assault gliders and hollow charges) were kept secret.
A propaganda film, shot on location in the months after the attack, gives great emphasis to the role of
the"Wehrmacht"  (army) over that of the "Luftwaffe" (air force). The dramatic footage (featuring large explosions, smoke grenades and German machine guns acting as Belgian defensive weapons) portray German soldiers wearing the characteristic regular army steel helmets but show neither gliders nor the use of hollow charges:

Nonetheless, we found two period photographs of German soldiers carrying the components of a 50 kilogram hollow charge:

(click on the thumbnails to enlarge)

Fort Eben Emaël Today

At present the fortress is open to the public on one weekend in every month. Reservations can be made for guided tours through the 5 kilometer long tunnel system with visits to the – still working - retractable gun cupolas, the huge steel stairwells and the plateau.

(click on the thumbnails to enlarge)

A modest museum features an example of the 50 kilogram hollow charges used, among other targets in the fortress, against “MAASTRICHT II” casemate:

(click on the thumbnails to enlarge)

Reenactment of the attack on Casemate Maastricht II

On Sunday May 16th 2010, little over 70 years after the attack on the fortress, reenactors in period German and Belgian uniforms demonstrated the glider landing, the capture of the anti-aircraft machine gun crews and the detonation of a 50 kilo hollow charge on the "EBEN III" steel observation dome on top of "MAASTRICHT II". was there and we registered the following sequence of events:

(click on the thumbnails to enlarge)


These images are a mix of what was shown to the audience on the fortress’s plateau and a subsequent exclusive demonstration for this website by the (Dutch) reenactor who played the role of Hans Niemeier, the squad leader of "Truppe 1" (section one) of the "Granit" assault group.
The images clearly show the distinctive method of transportation of the two components of the hollow charge, the relatively flat lower component, the larger bee hive shaped top and the insertion of a time delay fuse.
In the demonstration for the public, a Styrofoam replica was blown up with pyrotechnics.
An accurate steel replica was used in the closer up demonstration for

Belgian Veteran of the May 10 1940 Assault

Also present was a Belgian veteran of the artillery units of Fort Eben Emaël. He is Georges Cavraine from the city of Herstal and is one of the last living Belgian veterans of the fortress's garrison.

(click on the thumbnails to enlarge)

Georges explained to us that he had been stationed inside the fortress on that fateful 10th of May 1940.
He also told us that this was the third time he had been back at the fortress since World War Two.

Note the stark contrast between this survivor of the violent "Granit" assault and the reeanctors posing as conquering warriors:

(click on the thumbnails to enlarge)


Back to Case Files

(c) 2007-Present Day Email: all rights reserved.