ERDC REMEMBERS D-DAY U . S .
A R M Y
E N G I N E E R
R E S E A R C H
A N D
D E V E L O P M E N T
75TH ANNIVERSARY
W R I T T E N
B Y
G O R D O N
A .
C O T T O N
C E N T E R
" MUL B E RRY"
CAI S S ON
MODE L
I N
US E D
D- DAY
P RE P ARAT I ON
D-DAY BREAKWATER TESTS Gordon A. Cotton In addition to its role in the war as a testing
Thompson was considered the Army's
facility, the Waterways Experiment Station
outstanding expert on assault techniques
(now the U.S. Army Engineer Research and
as practiced by both U. S. and enemy
Development Center (ERDC) ) also
combat engineers; and he planned the
provided some key personnel in the Allied
Allied training center in England,
operations. Of interest to many in
supervised its construction, and operated
Vicksburg was the fact that former WES
it. When D-Day arrived, the troops had
Director Col. Paul W. Thompson was
been well rehearsed. And when those
formulating the invasion program for the
troops, trained by a former WES Director,
Allies. It was Thompson's job to see that
went ashore on Normandy, their invasion
both the infantry and engineer
was made possible by studies performed in
contingents, who would spearhead the D-
Vicksburg at WES .
Day invasion, were ready for the assignment. Thompson began conferences
Two artificial harbors tested at WES, then
in May 1943 with officers from every branch
built in secrecy and towed across the
of the service, British and French as well as
English Channel behind the assault forces
American, who had had experience in
for installation on the Normandy beaches,
combined operations or had knowledge of
were used to furnish supplies to the
coastlines and fortifications in Europe.
invasion armies and, according to a Â
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statement from Supreme Allied
The caisson models were placed in the
Headquarters, "made possible the
tank and subjected to waves simulating
liberation of Western Europe."
storm conditions that could reasonably be expected off the French coast; every
WES engineers, who had spent untold hours of tedious toil testing models of the artificial harbors, had already predicted the outcome. A decision to use artificial harbors had been made by British and American officials at the Quebec Conference in the summer of 1943; French ports could not possibly have the capacity for handling the needed stores to support the invasion, they reasoned. Almost immediately WES engineers were given the job of testing model harbors. Two
reaction was noted, and any flaws in the original design were corrected, then the new design tested until one was found which could be expected to withstand the final test. To aid in the structural design, pressures were measured at various points on the face of the caissons, and studies of tide and wave action were made to ascertain the stability of the sections with respect to overturning, settlement, and sliding. Determining the proper amount of ballast to be used where the sections
MADE POSSIBLE THE LIBERATION OF WESTERN EUROPE
proposed types of concrete caissons were
showed a possibility of movement was also
built to scale. One building at WES
done by testing; in this manner, spacing of
contained a huge wave tank and was
the caissons was also decided. Final data
equipped with intricate measuring and
were flown directly to England from the
recording devices. Crews worked for 7 days
Office of the Chief of Engineers. In England,
a week, 24 hours a day, for several months
the full-size caissons were constructed.
until the final test was made in December 1943. The task was so urgent that the usual
Gerard H. Matthes, WES Director, gave
written reports were discarded; as soon as
credit for the success of the tests to Capt.
some important fact was determined, it
Joseph B. Tiffany, Jr., Fred R. Brown, Robert
was transmitted immediately to
Y. Hudson, and Eugene H. Woodman, who
Washington.
spearheaded the work. Woodman devised the measuring and recording devices used in the tests while the others did the hydraulic work. 2
Among the changes in the original models
personnel who had worked for months on
which experiments showed to be feasible
the project must have experienced a great
was the shape of the caissons' tops. The
deal of satisfaction at the success. Now
originals were slanted, but tests revealed
their families and friends knew what
that waves would go over the slanting
project had consumed so much of their
summits and strike the caissons in such a
time and interest for so many months.
way as to endanger their stability. The tops were changed, the tests were repeated,
Joseph B. Tiffany, Jr., Executive Assistant to
and the trouble was eliminated .
the Director of WES at the time, recalled 30 years later the worry the project had
When D-Day came, one of the worst
caused him. He had figured out
channel storms in history wrecked a harbor
where the invasion would take place
before it was completed but after it had
because of the specifications concerning
already contributed greatly to the stream
tides, he said, and then he wished he did
of men and equipment pouring into
not know for fear that "it would slip out in
France. The other was finished as planned.
conversation, or that I might talk in my
It was a port as big as Dover, complete with
sleep" and accidentally reveal the military
docks, piers, and breakwaters, and was
secret.
capable of unloading at least 12,000 tons of stores and 2,500 vehicles each day. The ports had been built in three sections-
Click here to read "A History of The
blockships, caissons (sea walls), and
Waterways Experiment Station: 1929-1979."
breakwaters. Sixty old ships were sunk to form the five small breakwaters along the French coast. Included in the harbor construction were 150 caissons of six different sizes to suit various depths of water up to 33 feet. The largest caisson displaced 6,044 tons and the smallest 1,672. Towing the caissons and other equipment was done with 85 tugs and 500 tows in the face of enemy attack, and staffs and personnel had to be trained. Only a few tugs were lost to enemy action as they crossed the choppy waters at an average speed of four knots. Construction of the caissons alone had employed 20,000 British laborers, and many thousands more were engaged on other structures for the artificial harbors. The whole operation was far larger and more technical than most would have imagined possible, and despite the number employed in their construction, there was no case of leaking vital information. In Vicksburg, WES
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