Part One; Section I: IntroductionPart One; Section III: Location of Enemy Batteries and Mortars by crater analysis
TM E9-1901 - IDENTIFICATION OF JAPANESE SHELL AND SHELL FRGAMENTS;
LOCATION OF EMENY BATTERIES

PART ONE - GENERAL

SECTION II - SHELLING REPORTS (SHELLREPS)

3. GENERAL.

a. Whenever or wherever enemy artillery, rocket, or mortar shelling is observed, it must be report back immediately to where the information can be evaluated and acted upon. These shelling reports, now commonly called "shellreps", are rendered through channels according to a definite procedure and form by the individual or unit observing of exper-iencing the enemy fire.

4. VALUE.

a. Shellreps are basic and extremely valuable information; they are literally the key-stone of efficient counterbattery or counter mortar intelligence. In addition to helping lo-cate enemy guns speedily, shellreps:

(1) Tell when enemy guns are firing.

(2) Indicate which batteries are active.

(3) Indicate number, caliber, and type of guns firing.

(4) Report effectiveness of enemy shelling.

(5) Indicate zones of fire of enemy weapons.

(6) Indicate new locations.

(7) Make possible prompt retaliatory fire when location of offending batteries is estab-lished

(8) Serve to alert sound and flash, air OP's and other agencies.

b. The value of shellreps depends chiefly upon:

(1) Their accuracy and completeness.

(2) Speed of transmission.

(3) Number received.

c. Because silencing of enemy batteries is of vital interest to all soldiers, all should be encouraged to submit shelling reports, regardless of arm or service. However, a smaller number of reports which are complete and accurate are of greater value than many re-ports of a general nature. The best reports, therefore, are sbumitted by trained men who have actually surveyed the craters in the shelled area and have either analyzed the available shell fragments of submitted them for analysis along with their reports. Since a high percentage of all enemy concentration will fall somewhere near an artilleryman, ar-tillerymen should be especially trained so that their reports will be accurate, complete, and promt.

5. ACCURACY.

a. Shellreps are usually based upon hearing, visual observation, or crater analysis, or sometimes a combination of these. Reports based on hearing are generally unreliable as to direction. The human ear is not capable of judging direction better than an accuracy of about 5 degrees, and there are many other factors that will tend to make reports even less accurate. The most reliable, accurate, and informative reports are based on crater analysis, explained in the next section, or based direct visual observation of the flash of the enemy weapon, measured by an aiming circle, BC scope, or similary accu-rate, properly oriented, sighting device.

6. SHELLING REPORT FORM.

a. A suggested form for obersever's report to his headquarters is form "A", page 28. This form is suitable for printing on a card to be glued into the Field Message Book. Form "B", page 29, is suitable for recording this information at battalion and higher headquar-ters as the report are received.

b. The following is a detailed explanation of the purposes of the imformation required in the shellrep form (page 28):

(A). Time and unit reporting: Needed for furture reference.

(B). Location of observer: Accurate location of the observer is essential in plotting repor-ted azimuth. When crater analysis is made of several craters in same shelling, average of coordiantes should be given.

(C). Azimuth of direction from which shelling came: This is determined in any of three ways:

1. Sound. Estimation of direction by ear is too inaccurate, except for very short distan-ces when such inaccuracy is not as important as at greater distances. It should be used for mortar locations only.

2. Furrow or Carter. This method is most reliable and most accurate. Experiended ob-servers can get within 5 to 15 mils in a single compass reading which should not require more than 5 minutes. An average of several readings will greatly increase accuracy. Al-ways state the compass reading in magnetic north or grid north. An aiming circle will give more accurate direction.

3. Flash. An accurate means of obtaining direction to enemy gun is by direct measure-ment of the visible gun flash through a properly oriented, accurately located aiming cir-cle of BC scope.

(D). Distance in yards should be given whenever possible. The slope of fall in mils, when obtained in crater analysis, is usually of greater value than the estimated distance or location.

(E). Coordiantes of the are shelled are valuable as they may indicate the enemy intenti-ons. Accuracy of the locations aids in eliminating duplicate reports.

(F) and (G). Time "From-to": Should be given accurately. It may be that the shelling can be that the shelling can be tired into sound flash locations which were taken at the same time. Also, reports of two or more observers may be tied together, permitting ar-tillery to locate and neutralize the correct gun location immediately without wasting time and ammunition in firing on a dozen different targets with only a "hope".

(H). Number, caliber, and type of guns: The principal method of determining the number of guns is by the time interval between bursts or the number of bursts which come practially simultaneously. Character of sound is sometimes an indication of caliber to experienced personnel, but fragment identification is a positive and more reliable met-hod of determining caliber and sometimes type of enemy guns. Type of gun, whether howitzer or rifle, as well as caliber is valuable information and should be determined whenever possible.

(I). Number and type of shells: Number of shells falling into an area as well as type (HE, smoke, time, etc.) may give us a real clue as to what the enemy is trying to accom-plish. It can also indicate the amount of ammunition available or the importance of the target to him.

(J). Nature of fire: Counterbattery, registration, harassing, interdiction, OP neutralization, preparation, etc.

(K). Damage: The damage done will often determine counterbattery priority. This infor-mation should never be sent "in the clear" on voice radio or if telephone wires may be tapped by the enemy.

(L). Flash-bang (seconds): A flash-bang report is of exceptional value as it not only gives accurate direction but also approximate range to enemy guns. The method is simple. Time is taken at sight of flash (stop watch is highly desirable), then the obser-ver hears the report (bang) of the gun shooting (not he ballistic "crack" or sound of the shell in the air) and time is again noted. Since flashes are seen instantenously, and it is known how fast sound travels (approximately 370 yards per second), the time interval indicates range. Because of lag in individual reaction time, a correction of approximately 200 yards should be deducted from all ranges determined by this method.

(M). Remarks: Enter here anything especially noted.

7. REPORTING NWE SHELLS.

a. Shells or fragments found to have characteristics unlike those listed in this manual should be reported immediately to proper authorities.

b. To be maximum value, fragments sent to the rear should be tagged with the follow-ing information.

(1) Time (date and time of day shell landed, if known).

(2) Location (place where shell was found as accurately as location can be given.

(3) Direction (approximate direction from which shell came and method used in deter-mining that direction (survey of crater, sound, etc.)).

(4) Name and organization of person making report.

(5) References.

8. STANDARD OPERATING PROCEDURE.

a. A standard operation procedure for shellreps is recommended. The following is a sug-gested SOP:

(1) General Shellreps. Personnel in units of all branches immediately report hostile shell-ing, giving the following general information:

(a) Time.

(b) Where.

(c) Apparent direction to enemy guns.

(d) Number of guns firing and apparent caliber.

(2) Crater or Team Shellreps. Artillery personnel, learning of this hostile shelling through own observations of through general shellreps, dispatch trained teams immedia-tely to the shelled areas, including those from which general shellreos were submitted by other arms. These teams will make crater analysis and requisite survey.

(3) Teams. Each team consists of two men equipped with aiming circle, calipers, flex-ible steel rule, gunner's quadrant (when available), and dia-meter of substitute. The Compass M2 can substitute for an aiming circle.

(4) Each artillery battailon maintains three teams, each higher headquarters maintains one, and the observation battailons maintain four. In addition, the artillery forward ob-server, the artillery liaison section, and the infantery company teams also make crater analyses (primarialy enemy mortar craters) using prismatic compass only. Unless artillery battailons or higher artillery headquarters direct otherwise, teams automatically assume the following responsibilities:

(a) Direct suppor battailons for areas actually occupied by infantry.

(b) General support battailons and higher artillery headquarters for areas within 1,500 yards of their location.

(5) Completed reports are forwarded immediately, usually by telephone, and coded if reported by radio. Time of the actual shelling is reported accurately. Direct support artil-lery acts on mortar shelling reports ("mortreps").

(6) Any knowledge of hostile shelling beyond the limits of responsibility listed in step (4), above, is forwarded to suitable artillery haedquaters for survey.

9. PERSONNEL AND TRAINING REQUIRED.

a. A single individual can perform the necessary operations in each area; however, for speed and other practical considerations, a crew of two or three is recommended.

b. Inexperienced personnel can get accurate direction from ricochet furrows with very little instrcution. More instruction or experience is necessary in the case of craters, cer-tain types of ricochets, and for indentification of fragments. Kownledge of the elements of exterior ballistics, Firing Tables, and their use is helpful, but kownledge of enemy am-munition and weapons is definitely necessary. Since the enemy may use captured wea-pons against us. familiarity with weapons of our allies is important.

c. Instruction should be by trained personnel who know shell crater analysis and shell fragmentation identification from actual experience. There are many fine points to crater analysis. For example, the slope of ground, the texture of soil, the over-all detonation pattern, etc., all have definite effects that can be compensated for, if known, in deter-mining direction to the gun. Properly trained soldiers can select at sight craters giving most accurate results, and known where to find, with minimum effort, shell fragments most easily identifiable. Scouting and patroling should be emphasized so that maximum advantage is taken of terrain for protection against enemy fire.

d. It is often difficult to differentiate between hostile mortar and artillery shelling. How-ever, there are basically no differences in the techniques for locating enemy mortars and artillery. Therefore, instruction of both shellrep and mortrep teams can and should be given at the same time.

Part One; Section I: IntroductionPart One; Section III: Location of Enemy Batteries and Mortars by crater analysis