Evolution of the United States Army Signal Corps

By General A. W. Greeley

Chief Signal Officer, USA

General Greeley in his Office at the War Department

It may seem incredible, but it is none the 1 less true that in an electric age which daily garners the news of the earth for commercial and popular use, the question of instantaneous communications, as an impor­tant war factor, has failed fully to impress itself on either European or American tac­ticians. In the United States the standard textbooks of the American army, "Security and Information" and "Art of War," con­tain not even a page of matter on electrical communications.

This condition of affairs in America may be said to emphasize only the fact that we are a peaceful nation, and have been content to ignore advances in the science of war. In Europe, however, where progress in military science is considered scarcely second to that of commerce or industry, there has been, on the part of recognized authorities, a similar lack of appreciation as to the great value of electrical communications in war.

In Germany the latest and most important exposition on war factors and their practical application is found in Lieutenant-General von der Goltz's "Conduct of War," which does not contain even a paragraph on the tactical or strategical value of telegraphic or telephonic communications. Derrecagaix, the French writer, in "Modern War," bare­ly alludes to the subject in less than a dozen lines.

Colonel Thompson Flagging Navy to

 Cease Bombardment Pending Assault on Manila

An English writer, General Hamley, a student of our Civil War, pointed out in 1873, in "Operations' of War," Sherman's constant use of the telegraph in his flanking operations in Georgia. Hamley indicates the value of field telegraphy, as not only afford­ing simultaneous intelligence from distant parts of an army; but also as enabling the general to give the movements of his army on an extended front a decisive and co­operative character, so as to impart unity as to time and object of movement.

Hamley was so much gratified when his views were later confirmed by the campaign of 1877, in Armenia, that he dwells on it particularly in his fourth edition, 1878. He points out that the Russian commander-in­-chief, through telegraphic facilities, which the Turks ignored, not only rescued his army from conditions certain to be fatal, but by telegraph arranged a combined attack and destroyed the Turkish army. The lessons taught by Hamley have not been without their effect on the British army, as recent campaigns of Roberts, Wolseley and Kitch­ener disclose to the student.

Upon this subject, however, the writer said in 1892: "Too many officers regard sig­naling, either visual or electric, as valuable only to expedite communication, but the competent general wisely views this military arm in the highest light, as being especially important for tactical purposes, and as in­dispensable to the success of important strategic operations, wherein the complete control of separate but co-operating com­mands is necessary. The great tactical value of visual signals was evident at Yorktown, in connection with the military balloon; at Malvern Hill, in directing the fire of co­operating gunboats; at Fort Fisher, where, during the actual assault, the fire of the navy was changed from traverse to traverse, as the Union forces gained ground; and Farragut's attack in Mobile Bay. The strat­egic value of military telegraph lines is too evident to make it needful to dwell there­on.”

Flagging Santiago Transports at Camp Wikoff

The indifference in America seems the more striking when it is considered that in this country not only have visual signaling, telegraphy and telephony been invented and developed, but that in the United States they were first applied to actual warfare. Nevertheless, the conditions have been so adverse that it was only by strenuous exer­tions, and partly on personal grounds, that as late as 1891 the Signal Corps of the Army was saved from obliteration and an inadequate organization of ten officers and fifty men effected. Its subsequent mainten­ance and continuance have involved no end of effort and struggle, as the corps was yearly decried, repeated steps were taken to abolish it, and its annual appropriation was for years restricted to $3,000.

As to the Spanish-American war, one offi­cial report says that the Signal Corps entered it under the necessity of justifying its existence. How far it succeeded is evident from the extended and appreciative com­ments by military commanders in their re­ports on the operations of the Signal Corps. These cover military administration in the great camps of the United States; installa­tion and management of submarine cables, telegraphs and telephones in the Santiago campaign; military operations in Porto Rico; and the campaign culminating in the cap­ture of Manila. There is but little question of results detrimental, if not fatal, to the American army and to the interests of the United States had such communications been absent during the siege and after the sur­render of Santiago. In the Philippines, the late brilliant field operations under the direction of General Otis, by Generals McArthur and Law­ton, have strikingly illustrated the util­ity of visual signal­ing, of telegraphy and telephony.

Spanish Heliograph Tower at Ciego d'Avila

General McAr­thur, an accomplish­ed officer with a previous extended experience in the civil war, says on this subject:

"As a means of tactical control, wire service in the hands of trained, skillful and fearless men may be regarded as an indispensable adjunct of war, in which light it is a great privilege to speak in be­half of the future development of the Signal Corps of the regular establishment to the full limit of essential military useful­ness."

The work of the old Signal Corps was con­fined to visual signaling, with a brief at­tempt at field telegraphy. The operations of the modern corps are three-fold: 1st, visual signaling by flag or heliograph, by torch or lantern; 2d, electrical signaling by teleg­raphy or telephony; 3d, war ballooning, to which may be added the gathering and trans­mitting of military information. The pres­ent Signal Corps work is an evolution, its original basis being visual signaling, which as it now ex­ists is due to the inventive genius of an American, t h e late General Albert J. Myer, who de­vised a simple sig­nal code that has met with general acceptance. The Myer system pro­vided for the simplest possible alphabet and its means of signaling; a flag by day and a torch by night, were equally practi­cal. The alphabet, represented by combinations of the figures one and two, is as follows:

 When the flag, which is normally held erect, is waved to the right it represents one, and to the left two. There is a brief time interval between letters. The end of words, sentences and messages are shown respectively by dipping the flag one, two or three times directly to the front. This sys­tem, commonly known as the "wigwag" code, was first used in our late civil war, and it stands practically unchanged to this day. The only improvements in methods of flag signaling are a reduction in the weight and length of the flag staffs and a slight modification in the attachment of flags. Re­peated efforts to modify the alphabet have practically failed, owing principally to the inability of the Navy to use the American Morse or other similar system. Owing to its quite limited range, flag signaling is neces­sarily restricted, and its use is largely con­fined to intercommunication between the Army and Navy. Flagging can be read only from five to fifteen miles, the distance de­pending on the clearness of the atmosphere, the color of the flag, and the kind of back­ground against which it is displayed. As a rule, the white flag with a red center shows farthest, but against a light background the red flag with a black center is preferable.

The flag has been invaluable to military commands in many instances, the most strik­ing being the messages of General Sherman in October, 1864, when that resourceful offi­cer forestalled Hood's memorable plan to capture Allatoona with its three millions of rations. All other means of communication being cut off and the enemy intervening, Sherman signaled from Kenesaw Mountain over the heads of the enemy to Allatoona, eighteen miles distant, and ordered Corse from Rome to hold the depot at all hazards. In the fearful battle that followed his casual­ties exceeded seven hundred, but to Sherman's great relief, Corse flagged from Allatoona Oct. 6th: "3:15 p. m. I am short a cheek bone and one ear, but able to whip all h--- yet." Sherman said that these mess­ages were worth a million dollars to him.

In the Spanish-American war the fire of the Navy in the assault on Manila was di­rected by the army signal flag, and later in the insurgent war this method of fire con­trol for the Navy in its co-operation with the Army has been operated from Caloocan to Bacoor with an accuracy that has aston­ished all observers.

Field Telephone Station in the Philippines

In the Philippines neither administrative nor military co-operation would have been possible with the Navy except by means of the flag. In addition, the military sanitarium at Corregidor Island, about twenty miles from Manila, has been kept in constant communication with General Otis' headquarters.

During the civil war, night signaling was had by means of two torches, usually fed by turpentine. The foot torch, which remained fixed on the ground directly in front of the signalman, served as a reference point by which the receiving station might distin­guish between the right and the left motion. The flying torch, waved similarly as the flag, spelled, out the combinations representing each letter. Its limited range, slowness of operation and difficulty of handling were ob­vious disadvantages in the war torch, and effort to improve it by the use of asbestos and of brickwood met with slight success; in addition, its flame is visible only from six to eighteen miles, according to the atmos­phere. Recourse has been had, in late years, to signal lanterns, and probably a hundred different patterns have been alternately ex­perimented with, tested and abandoned as unsatisfactory. The discovery and practical utilization of acetylene gas, however, led to the construction and adoption of a .signal lantern. It is simple in its operation, works satisfactorily, and is visible to the naked eye as far as twenty-eight miles in clear weath­er. The signalman uses either the Morse telegraph code, making the dots and dashes by cutting off by a finger-key the light for short or longer periods, or by the wig-wag (Myer) code, where dots and spaces are used. Another method of using the lantern is to turn the light in its full brightness on the receiving station, when the signals are made by alternately displaying and conceal­ing the flame by means of a heliograph shut­ter.

Field telephone

It frequently happened that the operations of the Signal Corps covered stations too widely separated for the use of the flag, and for extended work it was essential to devise other methods. Flash signaling by helio­graph or heliostat had for years been in use for arbitrary signaling. It was thus that the sun-mirror of the savage Indian flashed mess­ages of terror from hill to hill. In civilized armies it was first adopted for general mili­tary purposes by the Anglo-Indian Army. Its advent in the American service was on the recommendation of General W. T. Sher­man, who had observed its operations in India, and on the favorable report of the writer to whom the whole subject was re­ferred in 1873 by General Myer. From that time the flashing sunbeam has done its part as a fleet messenger of war.

The evolution of the standard heliograph of the Signal Corps is a triumph of Ameri­can ingenuity, and in its methods and me­chanical construction differs radically from that used by the Anglo-Indian Army.

The English heliograph consists of a mov­able mirror with an attached finger-key to control its movements. To keep the mirror in adjustment during its operation an expert is necessary; in addition, the manipulation of the key necessarily causes a greater or less movement of the mirror, so that the image of the sun at the receiving station is often displaced. In the American heliograph one difficulty is entirely overcome and the other materially reduced. The transmission and interruption of the flash is effected by a key attached to the screen, which is mount­ed on a separate tripod. When closed the screen prevents the passage of the sun's rays, but when open the reflected image is distinctly visible to the receiving station.

The heliograph, under present conditions, can be used only during hours of sunshine, but on bright days its transmitted signals are so quickly displayed and promptly read at any reasonable distance that it replaces the flag on all possible service. Dust and smoke which would completely obscure the largest flag are readily penetrated by the flash of the heliograph. Under ordinary con­ditions, this flash is visible to the naked eye at distances of thirty miles, but with a tele­scope of thirty powers can be seen nearly two hundred miles.

Bicycle cable reel

The military value of the heliograph was strikingly illustrated in the successful cam­paign of General N. A. Miles against Gero­nimo, a campaign that put an end to the Indian outbreaks that for twenty years de­vasted Arizona with its horrible accompani­ments of murder and rapine. To and from barren mountain peaks, across and down into the arid valleys the sun-flash messages of the Signal Corps, directing our cavalry, marked the flitting of marauding Indian bands, whose war trails were marked with blood, from their home fastnesses of Arizona to the Mexican frontier. General Miles speaking of it as "the most interesting and valuable heliograph system that has ever been established . . . valuable in any In­dian or foreign war," adds; "They (the hostiles) found troops in every valley, and when they saw heliograph communication lashing across every mountain range: Gero­nimo and others, who had already surren­dered, sent word to Natchez that he had better come in at once," and he did.

The distance to which heliographs could be worked was tested under the able and zealous supervision of Major W. J. Volkmar in Arizona in 1890, when he established a system aggregating 2,000 miles in length. Ranges of 85, 88, 95 and 121 miles were successfully worked over. Previously the world's record was that between Mauritius and Reunion, where mirrors of 1,200 inches of reflecting surface, costing over $15,000, transmitted messages 117 miles. This was now surpassed by a signal corps mirror, of barely twenty inches surface, costing $40. These operations indicate the mechanical skill and deftness of manipulation of Ameri­can instruments and by American operators.

The most astonishing feat of long-distance heliographing by the Signal Corps was that accomplished through the skill and energy of Captain W. A. Glassford, September 17, 1895. With a standard instrument of the Signal Corps, a station heliograph eight inches square, messages were sent and re­ceived between Mount Ellen, Utah, and Mount Uncompahgre, Colorado, an air-line distance of no less than one hundred and eighty-three miles. This exceeded by fifty-eight miles the world's record, and will undoubtedly stand unbroken for many years. The great diffi­culty in establishing very long ranges consists in selecting points of such elevation as is necessary to overcome the convexity of the earth. Concerning the visibil­ity of the flash, Captain Glassford says, "When we caught the first glimmer of the Mount Ellen flash, it appeared through the telescope a deep reddish hue. It was about as bright as the planet Venus, and with the same apparent disk as presented by that planet in our glasses."

Field Signal Party with Cable Cart, Flags, 

Heliographs, and Telephone Kits

Foreign armies have repeatedly followed Signal Corps methods. The Spanish forces, unable to maintain telegraphic intercom­munication, utilized the American heliograph in Cuba. In the center of the celebrated Moron Trocha, at Ciego d'Avila, the Spanish army erected a tower 125 feet high, from which were flashed helio­graphic messages to Jucaro, on the south coast, and Moron, on the north of Cuba.

The old Signal Corps acquired its splendid fame by visual methods. The age has moved on, and now in war as in peace, electrical inventions have forged to the front, and their utilization is the distinctive feature of the modern Signal Corps.

The value of a field telegraph was obvious to General Myer, but his energy failed to secure results of practical importance. Failure was due in part to professional jealousies, but more perhaps to the lack of a proper system and suit­able instruments. Unfortunately, instead of adopting ordinary tele­graphic methods, he depended on Beardslee's system, where batteries were not used. The instrument used dynamo electricity to effect the synchronous control and move­ment of a pointer on both the sending and receiving instrument. By means of a crank a needle was revolved over the face of a dial, whereon were arranged the letters of the alphabet, figures, etc. The operator stopped the needle temporarily at a point opposite the first letter of his dis­patch, and by successive operations labor­iously spelled out his message. The lack of exact synchronism caused errors and many dispatches were unintelligible. One of the best signal officers of the Civil War states that to ensure prompt and correct de­livery he always started his message by courier simultaneously with its dispatch by telegraph, and frequently the horseman out-speeded the telegraph. However, the Beardslee instrument introduced the first telegraph to a battlefield, at Fredericks­burg, and, having indicated the possibilities, dropped out of sight.

 Signal Corps Lance Truck

The field telegraph at present in use by the Signal Corps has been constructed on other lines. Every effort has been made to assimilate for military purposes the various devices and inventions that in late years have added so much to the efficiency of the great telegraphic cor­porations of the United States. Whenever any inventor brings to the public attention a new or improved wire, instru­ment, battery, insulator or other appliance, the Sig­nal Corps gives it careful examination, and, if promising, puts it to severe field tests.

It thus occurred that the opening of the Spanish-American war found the Signal Corps with its means and methods of electrical work fully determined on, and accurately formulated. It had very few offi­cers and men, all carefully selected through promotion by merit, and a strictly limited equipment, but its officers were abreast of modern electrical inventions, and its enlisted men skilled telegraph operators, practical electricians and linemen. It needed only money and authority to develop this skeleton corps into a large organization, competent to build flying telegraph lines, to install telephone exchanges, to lay and operate submarine cables, and to construct and maintain electric light systems wherever and when­ever the military exigencies required.

The flying telegraph train had been brought to a high degree of excellence. With necessary instruments and batteries the weight is yet so light that the entire plant for one hundred miles can be carried in eight army wagons, to which suitable signal corps appliances can be readily attached. To insure speedy and satisfactory operations, wire, battery and lance wagons have been con­structed on lines conforming best to exi­gencies of field service, as disclosed by past experiences. The running gear is strictly interchangeable with that of army wagons; indeed, in all signal corps work the impor­tant principle of interchangeability of parts is invariably recognized.

The standard flying telegraph train for an army corps, which is the signal corps unit, provides instruments, batteries and material for the construction of one hundred miles of line. The bat­tery power is obtained from Eagle cells, one for every mile of line. The wire used is seven-strand, composed of six steel and one copper wire, weighing about one hun­dred pounds to the mile; for extraordinary purposes sixteen miles of this wire are highly insulated. The in­struments for sixteen offices and eight separate lines comprise sixteen sounding relays, sixteen vi­brators, type D, and two telephone switchboards. The special vehicles consist of two cable wagons, two battery wagons, eight lance trucks, and eight wire wagons.

A cable wagon carries eight miles of insulated wire, and in addition, two miles of light copper-armored cable, for crossing swamps, rivers or arms of the sea. These cables are mounted on six reels, by which they are readily distributed or recovered; in case of necessity, the reels can be removed and the distribution and recovery made by hand. Each wire wagon carries ten miles of naked wire, and is provided with instruments ant battery material, so that it may serve as a telegraph office.

The battery wagons are arranged for use as a central telegraph station, having batteries, blanks and everything necessary for intercommunication, and, in addition, are fitted up as telephone exchanges. A lance truck carries three hundred and twenty lances with detachable hard rubber insulat­ors. The lances are of tough, light wood eighteen feet long, and every fifth lance is provided with an extension butt five feet long, for use at road crossings or other im­portant points.

Night Signaling with Acetylene Lantern

Aerial lines of naked wire are usually con­structed, but in emergencies, such as exist­ed at Santiago and in the recent operations in the Philippines, the insulated wire is stretched along the road, or thrown into the underbrush, and thus used for days at a time. The effectiveness of the insulation is shown by the fact that it has constantly withstood the action of the elements, and in no in­stance has the wire failed in its insulation, except where it has been broken either maliciously by the enemy or carelessly and ignorantly by our own troops. At Santiago, pieces were often cut out to subserve in­dividual wants of soldiers.

It is a rule that insulated wire shall be re­placed by aerial lines at the earliest moment, and the wire be recovered for future use. In the Philippines the same insulated wire has been laid and recovered a dozen times.

During advances in an enemy's country, the Signal Corps utilizes every mile of avail­able wire, and it was by such method that General Miles' headquarters at Ponce, Porto Rico, was kept in touch with the four divi­sions of troops ad­vancing on separate lines. Over two hundred miles of line were thus built, and the tele­phone was frequent­ly operated on the firing line.

In General Mac-Arthur's march from Manila to Malolos, in the Philippines, the insurgents thought that they had effectively inter­rupted telegraphic communication by cutting down, at intervals, a mile or two of telegraph poles and carrying off the wire. It is need­less to say that these gaps were closed up promptly, first by insulated wire and later by aerial lines, so that the Signal Corps, keeping pace with MacArthur and his skirmishers, maintained telegraphic communica­tion not only with General Otis, but every detached unit of his command.

The Signal Corps has devised and improved many instruments for field telegraphy and telephony. The greatest single improvement is a device invented by Colonel James Allen, Signal Corps, known technically as a vibrat­or, type "D." It is a portable kit, weighing less than ten pounds, carried by a signalman, and is operated either with a telephone or vibrator. When inserted in a regular telegraph circuit it enables operators to simultaneously send two messages, either in the same or opposite direction, and also permits simultaneous use of the telegraph and telephone.

Heliographing with Two Mirrors

The system of field lines and telephonic exchanges has been supplemented by various devices for use in connection with detached parties and advance guards. One kit, an individual outfit, consists of a vibrator type "D" and a multiplying wire-reel containing nearly a mile of aluminum bronze wire, weighing only eight pounds, which enables the soldier to move forward to the limit of his wire and yet keep in constant communication with the station in the rear. When accom­panied by an assist­ant, he can advance more than two miles and lay out or re­cover the wire as fast as he can run.

For more im­portant operations the outpost cable cart is used in con­nection with grand guards and advance parties. This cable cart carries five reels of double-con­ductor cable, mak­ing it practicable to establish and main­tain communication by telegraph or telephone with troops advancing or operating in swamps or forests. For very rapid work of a temporary character there has been devised a bicycle cable reel, with which nearly a mile of light double-conduc­tor telephone cable can be speedily laid or recovered. In experimental work a mile of line has been laid, communication established and the wire recovered, in seven minutes. It should be understood that the bicycle reel and the cable cart are devices that can be used only over favorable ground. Under ex­ceptional circumstances they are of great value, but for important campaign work heavier material and stronger appliances are essential to withstand the rude shocks of war.

Work with war balloons during the Civil War was conducted by civilian aeronauts. It now forms a recognized part of the duties of the Signal Corps. The very great expense of aeronautical experiments deters the Ameri­can army from competing actively in this field. The Signal Corps watches closely the advance abroad in dirigible ballooning, es­pecially in France and Germany, while tak­ing at home an active interest in the devel­opment of Langley's aeroplane. Sample bal­loons are bought and a balloon maintained.

The great advance in war balloons con­sists in the use of steel cylinders wherein are compressed under two hundred atmos­pheres pure hydrogen gas. These cylinders are carried with the balloon, and it is possi­ble therewith to inflate and put a balloon in the air in thirty minutes.

Field Telephone Station No. 4 near San Juan Hill

The domain of the Signal Corps is not confined alone to the earth and air, but is now carried to the bottom of the sea. Only a few weeks since, the cable ship "Hooker" sailed for the Philippines with over two hun­dred miles of submarine cable manufactured in the United States in accordance with specifications issued by the Signal Corps. This cable is to be laid by Major J. E. Max­field, an officer of the Signal Corps, who fol­lows in the footsteps of Colonel Allen, the officer who laid the first submarine war cable in the world, on the south coast of Cuba.

The progressive methods of the Signal Corps are illustrated by the latest plan, that of having the cable and telegraph equipages fitted with electrical power. By the intro­duction of electrical automobiles, the battery power is present in such form that it can be used either in connection with telegraphic operations or as a motor, according to the necessities of the occasion.

Finally, the American Signal Corps, while claiming that its organization is the original basis of all foreign services of like charac­ter, recognizes that only by constant effort can it hope to maintain its supremacy among military corps of the world. To do this is the aim and intent of the American soldier.

From Ainslee’s Magazine, August 1899.