US History/US History (Bureau Development Inc.)(1991).ISO/dp/0084/00840.txt

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$Unique_ID{USH00840}
$Pretitle{79}
$Title{The Signal Corps:  The Emergency
Chapter VII-D Propulsion From Limbo}
$Subtitle{}
$Author{Terrett, Dulany}
$Affiliation{US Army}
$Subject{british
corps
radar
air
signal
equipment
research
war
aircraft
radio}
$Volume{D114.7:SI/V.1}
$Date{1956}
$Log{}
Book:        The Signal Corps:  The Emergency
Author:      Terrett, Dulany
Affiliation: US Army
Volume:      D114.7:SI/V.1
Date:        1956

Chapter VII-D Propulsion From Limbo

The Tizard Mission

     No other part of the Army was to figure in this union more closely than
the Air Corps, and the Air Corps drew the Signal Corps along in its
slipstream.  The Battle of Britain was about to open, the expected mass
attacks being prefaced by coastal bombings.  Each passing week which was
apparently building up to another dread climax was also indicating that
British air defense possessed a vital secret.  In addition to the Spitfires,
searchlights, barrage balloons, flak curtains, there was something else.  In
the United States, popular conjecture worked at large, but electronic
scientists and the inner circle of government could pin the answer down.  On
the British side, there was a similar shrewd understanding of the areas of
research which other countries might be exploring.  But the intelligence
channels which inform one government of another's secret activity run in only
one direction.  Both countries had every motive for opening up a two-way
passage, defense being the common denominator in their policy.

     Upon instructions from his government, the British Ambassador to the
United States, the Marquess of Lothian, broached the matter.  The British
"would greatly appreciate" it, Lord Lothian said, if the Americans, being
given the "full details of any [British] equipment or devices, would
reciprocate by discussing certain secret information of a technical nature
which [the British] are anxious to have urgently."  A startling rearrangement
of Atlantic power was even then being composed, under the color of the
exchange of destroyers for island bases.  What was asked was that the two
nations break tradition in another field, in order to exchange carefully
guarded technical information.

     Lothian hoped to avoid the show of a bargain; and, indeed, there was no
need for any, because unlike the plan for the United States to take over the
strategic defense of the western Atlantic, this agreement would not be
submitted to public discussion.  In fact, he proposed to the President,
"Should you approve the exchange of information, it has been suggested by my
Government that, in order to avoid any risk of the information reaching our
enemy, a small secret British mission consisting of two or three service
officers and civilian scientists should be despatched immediately to this
country to enter into discussions with Army and Navy experts."  Thus only a
few would be party to the vital secret, and of those few, all would be
"perfectly open" in telling what they knew, without jockeying for leverage.

     Some on the American side were suspicious of this; some, even,
subsequently felt that they had been required to surrender national advantage.
The Army and Navy held back their hearty concurrence.  "[The proposal is]
aimed at getting full information in regard to our airplane detector, which
apparently is very much more efficient than anything the British have," was
the Army's point of view, which nevertheless also recognized that the British
had their own detector and gun layer, as well as the pip-squeak system for
identifying aircraft.

     Some on the British side were inclined to fume that they had little to
learn from the Americans.  The relation would be an exchange of British
headwork for American handwork.  Lothian made it plain that what Great Britain
was particularly anxious for was permission "to employ the full resources of
the [U.S.] radio industry . . . with a view to obtaining the greatest power
possible for the emission of ultra short waves."

     This statement directed American concern to patent rights and to the
demands which might be made upon industry.  Its deepest significance, which
was contained in the reference to "the greatest power possible for the
emission of ultra short waves," was temporarily passed over, not to be
understood until the actual discussions brought it out.  Both sides had more
to learn about the other than they realized.  The truth was that probably
neither would have brought electronics to the maturity it quickly reached had
they not got together.  And had electronics lagged in the crucial two years
before the free powers joined military forces in Africa, the effect upon the
war would have been grave.

     However much basis existed for misgivings, the circumstances of the
moment overrode them.  The air was electric with peril.  The President
therefore lost no time in approving the plan, and, so soon as they could be
chosen and prepared, the members of the secret technical mission set out. The
mission was given the name of its chief, who was Sir Henry Tizard, rector of
the Imperial College of Science and Technology and adviser to the Ministry of
Aircraft Production, and the other civilian members were equally close to
their country's research effort and to the unnamed equipment which was fending
off the Germans.

     Along with three officers of the Royal Air Force and Navy, this group
arrived in the United States late in August 1940.  They were scheduled to
confer first with the Army (which was to say primarily the Signal Corps) and
the Navy, then with the civilian National Defense Research Committee. On
September 2 Tizard and Professor R. H. Fowler met the armed forces
representatives, in General Mauborgne's office.  The principal guest was Maj.
Gen. Joseph A. Green, the Chief of Coast Artillery, the branch for which
American military radar had been instituted.  Maj. Wallace G. Smith, specially
detailed there by General Arnold, represented the Air Corps.  The Navy had
sent three junior officers.  The seasoned radar men were in the Signal Corps
contingent.  It was an extraordinary moment.  National security, the most
powerful of official taboos, was about to be lifted.

     Neither the Army nor the Navy had caught up with the unusual
circumstances of the Tizard Mission enough to authorize it's disclosure, with
the result that talk was fenced at the outset.  Another result, ultimately of
astonishing effect upon the implementation of the Signal Corps, was that, with
the British scientists speaking more fully and being unhampered by the
necessity to disclose how much of what they were describing existed, a seed of
suspicion imperceptibly took firm root.  Quite without any Machiavellian
intent on any by's part, the impression arose, never thereafter to be
dislodged, that Signal Corps equipment was inadequate, insufficient, belated,
lamely derivative, and unworthy of any place in the same league with British
equipment.

     Hindsight makes it possible to say what position each was actually in at
the time.  Both had pulse radar equipment for the ground (although far from
enough of it to be emancipated from sound locators) and both possessed the
basic types, the searchlight-control, gun-laying, and early warning sets.
American searchlight control was probably better than that of the British;
neither gun-laying set was good; the aircraft detectors had reached equal, if
differing, stages of development.  That of the British gave a better
definition on the oscilloscope and also indicated the height of the target to
some degree.  U.S. technicians were still in the process of working out
height-finding characteristics, but they had devised lobe switching and
antenna tilting, and their equipment was mobile.

     In airborne radar, both nations, again, had been working in basic types,
except that only the Americans had created an altimeter.  Apart from the
altimeter, these types represented efforts at air-to-surface-vessel detection,
air-to-air detection or interception, and identification of friend from foe:
respectively jargonized as ASV, Al, and IFF.  In the airborne types, however,
the Americans had used beat reflection in their experiments.  The British had
airborne pulse equipment, to which the Americans were just turning after their
disappointments in the beat method, at that early stage of imperfect
understanding of its possibilities. Moreover, Great Britain had airborne pulse
equipment beyond the development stage and actually in operation.  The sets
were plagued by heavy and cumbersome, like the U.S. experimental models, but
they were in service in the war.  All in all, therefore, Great Britain and the
United States had followed separate routes to approximately equivalent spots,
eleven months of touch-and-go warfare having put the British a milestone or so
farther along.  None of this was precisely assessed at the time, and the of
British items made an enormous impression.

     At the first meeting, both sides began somewhat guardedly, referred to
their facsimile, teletype, and speech-scrambling devices, and arrived rapidly
at the fact that radio reflection was a mutual secret.  It was, as a matter of
fact, not a secret at all.  The Japanese had just begun to shift from the
Doppler method to pulse; the Graf Spee, scuttled so soon after the out break
of war, had radar; and the British themselves had shared much of their own
work with Frenchmen now subject to German pressures.  A very long distance
intervened, nevertheless, between the fundamental principle, which was known
in so many scientific circles, and the applications of it, wherein secrecy was
vital, and wherein lay a victory in a deadly race.

     When the Signal Corps representatives heard that the British had
apparently solved the baffling problem of satisfactory airborne radar, they
were immediately impressed.  It was air-to-surface-vessel equipment, Tizard
disclosed; it worked on the pulse principle, as the Aircraft Radio Laboratory
experimenters had believed would have to be true; and, although details would
have to be forthcoming from another expert more familiar with them, it used a
200-megacycle wavelength.  Two hundred megacycles indicated a wavelength of a
meter and a half, with correspondingly long antenna, one of the very things
that the Signal Corps had been trying to get away from; nonetheless, the
British had about fifty sets already installed and operating, and the
equipment had shown that it could find surfaced submarines within a radius of
five miles and a considerably larger target like a battleship as much as forty
miles away.  Such a development had tangibly brought British radar down from
the eleven meters of the enormous, fixed Chain Home towers to one and
one-half.

     American radar, which was mobile, had got down as far; but, Mitchell
explained, the Aircraft Radio Laboratory "had never tried pulse transmission
in the air."  Colton interposed that possibly the Signal Corps Laboratories
had slighted microwave pulse, but to go up into the superhigh frequencies
introduced "extreme difficulties" one of which, Mitchell came in again to say,
was a reliable vacuum tube.  The problem which they had in mind was that
microwaves, which may be expressed also in very short wavelengths - roundly,
10 centimeters - would use proportionately short antennas.  To receive an echo
from a pulse sent out over a very large antenna mounted on a height or a tower
was one thing, but to achieve a good echo from small antenna equipment would
be quite another.  In the first instance, the transmitting area was big enough
to accommodate an outsized tube which could produce outsized power, and send
the pulse out hard enough for some of it to be left to be caught on the
rebound.  In the second instance, everything would require a smaller scale yet
the power would have to be as great as ever.  Mitchell thought that a small
tube developing big power ought to be feasible, but acknowledged that it had
not yet been "completely developed."

     All of this no doubt fascinated Tizard and Fowler.  They had brought over
a model of just such a tube.  British electronic research, goaded by exigency
which American research had not yet felt, had turned to and solved the problem
with a tube which time later showed to be the greatest single contribution to
radar.  It was the resonant-cavity magnetron, an electronic vacuum tube, a
tube specially ted for a new science.

     In 1928 the Japanese scientists Yagi and Okabe had discovered that a
split-plate magnetron could oscillate at extremely high frequencies, yielding
wavelengths as small as 2 1/2 centimeters; but the power output was very low.
The same had been in 1931 and 1932 of the Westinghouse 10-centimeter
magnetron.  But from the split-plate magnetron a research team at the
University of Birmingham had now evolved a multicavity magnetron, which only
produced microwaves but produced them with force.  This resonant-cavity
magnetron thus was at hand, internationally, ready to give life to a multitude
of microwave radar devices. It was the heart of the transmitter; the klystron
tube, which amplified the echoes of the pulse, was the equivalent vital organ
in the receiver.

     On the cavity magnetron, accordingly, the two great powers came
electronically together.  At their second meeting, this time in Ohio, at the
Aircraft Radio Laboratory, both sides showed much less reticence.  The Signal
Corps had got G-2 clearance to reveal practically all classified technical
developments, including homing and instrument-landing methods, means of
aircraft recognition, bombing-through-overcast, filter control networks,
absolute altimeters, underwater and ground sound ranging, artillery spotting,
and everything else in the whole range from wire throwers to "death rays."
The British delegates explained that their electronic establishment had made
considerable progress with 600-megacycle (1/2 meter) equipment, but this
frequency was still not far enough up in the spectrum.  Later in the war it
turned out that in many uses, the longer radar waves were preferable to the
shorter.  The 11-meter Chain Home stations, for example, could detect the
German rockets of 1944 and 1945 better than microwave equipment could.

     But both nations had long-wave radar.  What they wanted was the microwave
applications.  The 200-megacycle British air to-surface-vessel detector was
limited simply to finding the vessel; a visual bombsight took over from there.
Pinpoint bombing would require radar of no more than one tenth that
wavelength.  The same thing was true of any other form of precision
bombardment.  Wellingtons, making attacks upon Germany which motion pictures
like Target for Tonight suggested were ruinous, actually were dropping two
thirds of their bombs at least five miles wide of any worth-while target.
Great Britain felt an urgent incentive to work out also an airborne set
capable of detecting other aircraft:  an Al.  Here, the large antennas which
they had managed to make the best of in ASV were quite out of the question,
for the airplanes to carry Al would not be big patrol bombers.  They would be
fighters, and small.  Anything larger than microwave antennas would also
project too broad a beam for this purpose, because the earth would intercept
the pulses which one wished to be repulsed only by objects in the air.

     Radio could never reach variety and flexibility until it could get rid of
great weight and length and size, without losing any of the power which went
with those qualities.  This was a matter of developing a giant's strength in a
dwarf's arm.  The resonant-cavity magnetron ultimately wrought the feat and
revolutionized what was already a revolution.

     But the magnetron was so new that the blueprints were still wet.  Deep
anxiety showed in the haste with which the Tizard Mission had been dispatched
to obtain mass production of the magnetron in the United States industrial
outlay and multiform application of it in the United States fertile research
organizations.  The newest of these, the National Defense Research Committee,
was about to set up a Radiation Laboratory at the Massachusetts Institute of
Technology; to this agent would be handed the challenge of microwave radar.
The Aircraft Radio Laboratory would limit its own microwave efforts to
engineering the equipment; and the Signal Corps Laboratories would keep their
research below about 600 megacycles, the area of relatively long-wave radar in
which the SCR-268, 270, and 271 had demonstrated the Monmouth laboratories
authority.  The immediate future of radar, which lay in pulsed microwaves,
above all in their airborne applications, became the specialty of Division 14
of the Radiation Laboratory, as well as of its only real rival in the United
States, the Bell Laboratories, where the first American version of the British
resonant-cavity magnetron took shape in the closing months of 1940.

     This commercial development was of course a Signal Corps choice; there
was no question of the Signal Corps having abdicated its prominence in radar.
The ensuing connection between the Aircraft Radio Laboratory and the Radiation
Laboratory became extremely and necessarily close; and the Signal Corps
Laboratories afterward entered the microwave field in connection with Division
14's gun laying set, SCR-584, the hairbreadth hero of the Anzio beachhead.

     In this summer after Dunkerque, however, with the Luftwaffe and the Royal
Air Force building up to the Battle of Britain, urgent attention was settled
more upon air devices than ground.  While the Tizard Mission remained in the
United States, there was much discussion about IFF.  Air combat over the
British Isles daily demonstrated the need for it.  The presence of increasing
numbers of airplanes in the sky compounded the risk that friendly ones might
be shot down, foes allowed to penetrate.  How important it might be to know
one from the other, Pearl Harbor would show. IFF could have drastically
diminished that disaster.

     Still an unknown number of months short of a war of their own, the
Americans had an identification development in initial stages only; this was
the RR, the Navy's interrogator-responsor system of radio recognition. The
British had gone from their Mark I model of an IFF to a Mark II version also
in initial stages but relied principally and riskily upon a system of
direction finders which intercepted a plane's coded radio transmissions, took
bearings upon them, and, from a general knowledge of both code and pesition,
identified the craft.  Both the Mark I and the Mark II of the British IFF
involved merely a receiver-transmitter aboard the airplane. Normally in a
receiving position, the set commenced to transmit when a radar signal alerted
it, returning another signal along with the normal echo.  The effect was to
intensify the reflection which the airplane itself was making on the
oscilloscope of a ground detector.

     The first order of business after the opening talks with the Tizard
Mission was to follow the British example and put pulse equipment, however
cumbersome, in the air.  The visiting scientists had acknowledged that their
own airborne pulse radar had to be "nursed along in order to keep in
operation."

     The Signal Corps had the means to do as much as that.  Arrangements
promptly got under way for elements of an SCR-268 to be tried out in an
airplane.  There was no question of including its antennas.  "No one ever
believed airborne antennas (Yagis) would be feasible at 2 or 3 meters [the
SCR-268's antenna length].  Even when the British sets were first received at
ARL there was much doubt as to whether anyone would take up a U.S. plane with
them."  The engineers on the project temporarily rigged up a single horizontal
dipole and mounted it on the nose of a B-18.  Then, since an airplane could go
to the radar set more easily than the radar set could go to the airplane, the
engineers had the B-18 flown to Red Bank airport, where they attached the
receiving antennas along the sides of the fuselage. There followed a hurriedly
designed transmitter, the SCR-268 receiver, a commercial oscilloscope, a
modulator to provide 4,000 pulses a second, and a gasoline-powered generator.

     On October 2, a date coincident with the departure of the mission,
preparations at Red Bank were complete.  Bad weather prevented test flights
there, the B-18 went back to Wright Field for no better luck, and it was the
beginning of November before airborne trials could commence.  In advance of
them, the crew kept the bomber on the ground and shot pulses at a basic
training plane five or six miles distant in the air.  The results were
distinct, for the basic trainer reflected pips upon the oscilloscope.  Had the
B-18 been flying, this application would have approximated Al.  On November 4
it did fly, from Wright Field over Lake Erie.  Now the equipment was being
tested as an ASV.  Up in the air, it surpassed the 6 miles of the ground test
and attained 17 against an ore boat, 23 against shore lines and islands.  This
was only half the distance the British claimed for their ASV, but for a first
try it was encouraging.  That the patchwork of components worked well at all
was proof of the soundness of the SCR-268 and of the engineering skill which
had adapted it.

     The Aircraft Radio Laboratory experimenters were under no illusions about
what they had.

     For practical aircraft use the transmitter, keyer, receiver, indicator
and power supply would all need to be completely redesigned mechanically. .
. .  Until a pulse less than a microsecond is obtained with the [Signal
Corps Laboratories] equipment or until equipment modeled after the 500
megacycle [Naval Research Laboratory] pulse altimeter . . . is completed,
flight tests on aircraft-detection will be suspended.

     This was the view of the ARL director.  The Air Corps view at Wright
Field was more sanguine, with the chief of the Experimental Section declaring
that "the results obtained from this equipment were very encouraging and show
that a means of detection of surface vessels from airplanes is available.  To
be made practicable, this equipment needs only to be reduced in size and
weight."

     British ASV arrived at the field within a fortnight of the Lake Erie
tests, though; and, inasmuch as it was supposedly ready to be Chinese-copied,
it was given right of way over any attempt to modify the SCR-268 for the same
purpose.  Thus the airborne SCR-268 experiment did not bear fruit as it might
have, if it had been tried several months sooner.  The Aircraft Radio
Laboratory did continue the work, with a number of sets under the nomenclature
SCR-519; one of these utilized the lobe-switching technique of the SCR-268,
but none of them materialized.  The first ASV and Al radars to see service in
the Air Corps were copies of British designs.

     Great Britain had first experimented with putting radar aboard aircraft
in 1937.  The Signal Corps had radar by then.  What were the obstructions
which had so long blocked the Americans?  Lack of free communication must bear
part of the responsibility.  No doubt can remain that with a readier flow and
exchange of knowledge, American Army radar would have had a much shorter
infancy.  "The 268 projects were kept so secret that few at ARL knew of them.
I did not," was the remark of Col. William L. Bayer, one of the half dozen who
first tested the SCR-268 components over Lake Erie.  Lack of funds, absence of
basic research, unflagging Air Corps attempts to absorb the Aircraft Radio
Laboratory also contributed barriers.  But the main reason why nobody up to
this point had got pulse radar up into the air was doubtless that nobody had
thought of it - a reason which directs admiration toward the British
scientists.  "It is easy to say now that the weight and size limitation might
have been overcome but it would not have been easy to visualize the 268 as
flyable. How the British [imagined] it still baffles me . . ."  Bayer's
tribute came from a man who knew the problems.

     Assessing the relative progress of British and American radar is a matter
of balancing one extreme against the other.  In the first place, radar
research in the two countries differed significantly in origin, and this
difference may be assumed to have advanced airborne radar rather more in the
United Kingdom than in the United States.  British radar was developed from
the first for Royal Air Force uses.  In the Signal Corps development the
interests of the air had been secondary, if not in determined at least in
point of time.  No radar undertaking specifically for the Air Corps d begun
until after the Coast Artillery the SCR-268, had shown itself to be good.
Then, although expressing itself vigorously in favor of the work, Air Corps
policy had made little more room for electronics than for radio.  This
observation is no sooner stated than it is overmatched by other, which must
also be taken within the context of the era.  Research and development for the
Air Corps which was carried on in other branches was no more hampered than in
the Air Corps itself; the list of airplanes with which the Air Corps entered
the war suffered even more by comparison with foreign design than did many
other categories of equipment. And this exception must in turn be excepted to.
No part either of the Army or of the public thought to fight the sort of war
which called for the impossible, at once - a war fought close to the shores
and thousands of miles away; an air, ground, and sea war; a high-, middle-,
and low-altitude war; a tropical war and an arctic war; a long war and a
succession of short wars.  It could not justly be expected that everybody
would be ready for everything, everywhere.

     The Germans were not, even after half a dozen years head start. Neither
were the British.  If British scientists suggested that Britain was advanced
in all forms of electronics, they were drawing a long bow.  If the members of
the Tizard Mission talked about what they were going to have as if they
already had it, they did so possibly because, being scientists, they thought
of the blueprint as the end product.  In the field, in action in the Battle of
Britain, "radio-location was in its infancy," "the teething troubles with
radar were enormous, it was bitterly disappointing," "the S.L.C. radar sets,
designed for searchlight work, were not due to come forward until the end of
February [1941]," and so on.

     Hard on the heels of the Tizard Mission's arrival in the United States,
American observers left for Great Britain.  They reported with conviction on
what they saw.  In the extreme of Signal Corps Laboratories opinion,
gullibility and superficial knowledge misled some of the observers, especially
in the Air Corps, into seeing more in British radar than actually existed or
would be suitable to the very different needs of the United States.  The
Laboratories radar men came to this conclusion after they learned that the
Chain Home's range was less than they had at first understood, that its
height-finding qualities were rough, and that the whole gear sacrificed
mobility.

     Against any line of argument which might have belittled British
accomplishment simply in order to exalt the U.S. achievement stood not only
the fact that the British had radar much farther in use but also the fact that
they had it more efficiently in use.  The Telecommunications Research
Establishment represented a pool of scientific knowledge from which Army,
Navy, and Air alike might draw.

     British methods of research and development were sometimes more flexible
and appropriate than American methods.  Their scientists did not carry the
laboratory work on a project too far or continue it too long. When a Mark I
had emerged, they cut short further development, and the interested arm or
service tried out the equipment, incomplete though it was.  Meanwhile, the
laboratory would start working on a Mark II, incorporating changes in it as
the tests of Mark I showed the need for them.  Mark III would presently
succeed Mark II.  In this way, a series of improved versions might come out
rapidly, logically, and with a minimum of instrument understanding between
technicians who might otherwise grow too remote from immediacy and users who
might be oblivious both of the problems and the difficulties of solution.

     The actual military organization for aircraft detection in Britain was
highly effective also; it showed few of the shortcomings which often left the
impression, especially in 1941 and 1942, that the American equipment, rather
than its operation, was inadequate.  Moreover, although the Germans attacked
the Chain Home from the beginning, the stations were hard to damage.  General
Chaney, a special observer of the Battle of Britain, visited one of the CH
sites a day or two after an attack which had knocked out two legs of a tower,
burned some of the buildings, and killed several girl operators.  The station
still functioned, guy wire holding up the tower, and there were wooden dummy
towers adjacent, both to confuse the enemy and to serve in the event of
further emergency.

     Chaney was an Air Corps officer, one of several who became devotees of
British radar.  Major Edwards, a Signal Corps representative, also liked
British design and recommended immediate purchase of the IFF and ASV
equipment, as well as of the very high frequency command radios which the
Royal Air Force used.  By far the most important sizing up was a quick trip
undertaken jointly by Maj. Gen. Delos C. Emmons of the Air Corps and General
Strong, the chief of the War Plans Division of the General Staff.

     Emmons and Strong found an England which everyone presumed would be
invaded and which some feared would succumb.  They were therefore all the more
impressed by the evidences of order, system, and progressive refinement which
they saw in the British defenses and scientific establishment.  The design,
construction, and organization of the command posts which formed the
corpuscles of Britain defense struck them particularly.

     The secret of the success of the operations [there, they noted] is rapid,
reliable and accurate channels of communications.  The British have installed
a very elaborate system of communications, consisting of the telephone, the
teletypewriter and the radio.  This must have been extremely expensive and
required years, but it is the framework upon which the defenses of Britain are
built.  If England successfully resists an invasion it will be because of
this. . . .  The fact that an airplane can be picked up by a radio watchman
and its position, direction of flight, and so forth reported to a fighter
station in a matter of seconds is illustrative of the care with which this
system has been designed and of its value.

     Emmons and Strong also learned of the AI and ASV, respectively the
air-to-air detector and the air-to-surface-vessel detector.  They did not see
an Al, and the British confessed that it was "in limited use at the present
time."  Actually, the first one had just been ordered.  They saw the
pip-squeak method of identification, with its use of a visual signal, a plume
of smoke shot from the tail of the fuselage when the airplane was coming over
a friendly anti-aircraft battery or wanted to signal that it about to attack.
And above all, they saw the three principal sets, roughly corresponding to the
three which the Signal Corps had developed.  They liked all three, and urged
that the Signal Corps delay not an instant in dispatching a man to learn from
the British book.

     Thus one of the most significant Signal Corps involvements of World War
II began.  In less than two months time from the arrival of the Tizard
Mission, Signal Corps research had forsworn the sands pit isolation where it
had wielded its own radar and had been irrevocably committed to full
participation in a world conflict.  Departing from the United States to return
to England, Tizard said:

     From our point of view our visit has been a great success, and I hope it
has also been of value to [the Americans].  The British Government are only
too anxious to have as full as possible cooperation in all scientific and
technical developments and I hope the interchange of important technical
information will not cease or diminish on our departure.

     It did not.  Under the example of the leaders of the two nations,
President Roosevelt and Prime Minister Churchill, cooperation was the order of
the day in all enterprises, an order unchanged year after year.  The Tizard
Mission and the simultaneous Minerva-birth of the National Defense Research
Committee (Dr. Vannevar Bush was Jupiter) had pointed up one form of
co-operation aside from the international.  This was the desirability for
collaboration between soldiers and civilians.  Englishmen associated from the
beginning with the Telecommunications Research Establishment have not
hesitated to say that its great work could never have brought so many
victories had the Air and War Ministries not recognized their dependence upon
civilian intellectuals who were following what often seemed undisciplined
courses of thought.  Science had advanced by the cooperation of scientists,
and military science could advance only by encouragement of the same freedom
of investigation and intercourse.  At the least, the double collaboration
between science and army, Great Britain and the United States, rescued
millions of persons from agonized prolongation of the war.