There are different reasons to consult the records of the National Archives – subjects may be topical, such as submarine mining, or geographic, such as a particular fort or harbor defense. Those just starting to do research on a geographic basis can find the archives confusing. Entirely too much time is spent re-inventing the wheel – searching for records that someone else has either seen or knows where to locate. It is hoped this article will decrease this, and encourage the sharing of information found in the archives.

This is by NO means a complete guide to the resources of the National Archives. It is only intended as an introduction, a guide to the first level of basic research. Starting and ending dates given for different entries are not absolute, and the files often contain documents dated before or after the years given.

It should also be noted that one of the most important record groups, RG 392, Records of the Coast Artillery Districts and Defenses, has been transferred from the Washington, D.C., archives to the various regional archives.

General

The National Archives largely contains the records of Federal agencies. While both their library and holdings contain some published works, the National Archives is primarily a repository for unpublished documents, divided into several hundred “record groups.” For example, the records of the U.S. Army are contained in many different record groups, including those for the Office of the Chief of Ordnance, the Office of the Chief of Engineers, and two for the Adjutant General’s Office.

These record groups are subdivided into “entries,” sometimes called “series.” To assist researchers, there are two types of listing aids at the archives. “MLRs” list each entry in a record group and give a brief description of the contents, showing the size of the entry and where it is located on the shelves at the archives. One complication is that some record groups, for reasons never explained, have more than one entry with the same number, so the descriptive title of the entry and its shelf location are important. In addition, descriptions of the entries are often less than complete, and sometimes so cryptic as to be meaningless.

The second source is the “finding aids.” Compiled by the archives to aid researchers and often containing better information on the content of the entries, these may list the contents of an entry box by box. However, finding aids do not cover every entry of every record group, and for some large entries, the finding aids amount to many dozens of notebooks.

At the downtown Washington, D.C., archives, the MLRs and finding aids are in the archivist’s office. For military records, this is on the first floor, behind the elevators. The archivists are also located in this room, and can be conveniently consulted.

At the College Park archives, MLRs and finding aids are kept in the glassed-in room off the textual research room on the second floor. For further help, the archivists are in Room 2400, which also contains MLRs and finding aids, sometimes more extensive than those in the research room. A researcher must receive a pass and be escorted to Room 2400, although an appointment is usually not necessary.

Archives I, Washington, D.C. – c. 1894 – 1917

During this period (roughly the Endicott-Taft era), records on forts were usually kept in the general record files of the different departments and branches. Each department used a numerical file number to create and identify separate files. Unlike the later military decimal system, the numbers themselves do not indicate what the file contains, and there is no relation between adjacent numbers or between numbers assigned by different departments. File numbers were simply assigned chronologically as a topic or need arose. Topics are mixed – a number assigned for “New 3-inch battery to be built at Fort Mott” may follow a number about granting leave to a clerk somewhere and precede a file concerning major civil engineering work. Therefore, browsing just does not work. You need to locate a finding aid, index, or some reference giving the precise number of the file needed and you must then request the box that has that file in it. Within the file the individual letters or enclosures (designated by a slash: file 37455/1, 37455/2, etc.) are usually arranged chronologically.

Multiple files may exist on a single subject. Files begun before a fort was named and listed simply by the geographic location (i.e. Great Gull Island or Clark’s Point) may not be consolidated with files created after the fort was named (i.e. Forts Michie or Rodman).
At times files were set up in “waves.” Some new appropriation or initiative would create a new generation of fire control stations, mine casemates, or searchlights – and the engineer office would allocate 28 new numbers, one for each harbor defense. They did not go back and use the last number for that port and that item. Often after 3 – 5 years without a new entry, a number was not continued as an active file, and a new number was created if the topic came up again. Thus there may be four or five major files on subjects like “position finding,” “submarine mining,” or “electrification.”

The hierarchy of how the information was organized also varies. Some topics were the natural concern of the harbor defense. For example, general defense plans and projects were always created and filed for the “Defense” (e.g. Portland), and not an individual fort (there is no defense project for just Fort Williams). On the other hand, individual gun batteries were appropriated, designed, approved for construction, and built. Thus there is no file for “Batteries in Portland, Maine,” or even for “Batteries at Fort Williams,” but rather there is a file for each individual battery – Battery DeHart (and from the above example – “1897 battery for 10-inch guns at Fort Williams”), etc. Less frequent were topics handled only at the regional level and the service as a whole – though you can sometimes find a summary report in a specific file – “status of modifications for chain hoists,” that has an entry for each and every location. Thus to try and cover the information on a fort you also need to look up the individual batteries or topics about the fort, and also look a level or two higher into the district or region of the command responsible. Fortunately, the index cards generally recognize this and multiple entries of a file exist on numerous cross-referencing cards.

One key to using the index cards is to be creative. Files on batteries are indexed by the battery name, but files created before the battery was named may be filed under the fort name. Similarly, other names for forts should be checked, such as the name of the geographic location. In addition, the cards for the harbor defense should be consulted. As an example, for Battery Bradford, on Fort Terry, the index cards for “Bradford,” “Terry,” “Plum Island,” “Long Island Sound,” and “New London” (the original name of the harbor defense) should be requested.

These record systems usually have file card indexes, large collections of up to several hundred boxes of file cards. Arranged alphabetically, they list a topic, and then have listed on them (at first handwritten, later typewritten) a short (sometimes cryptic) description, sometimes the name of the author, date, and file/letter number. For some forts there may be 30 double-sided file cards holding hundreds of records. These can be used to identify specific records to look at – or also as a shortcut for more productive browsing. If file #17652 shows up a dozen times in 1898 – 1901 it is likely a major file with specific letters about a key battery or subject you are interested in. Often 10 – 12 file numbers will provide a good coverage of a fort. It does take a little knowledge and sometimes some dead-ends to catch on to the alphabetical protocol. Forts and batteries are listed by name – and not under “F” for fort or “B” for battery. However, all specific gun sizes are listed numerically under “G” for guns or “M” for mortars.

At times files were destroyed or discarded – sometimes a note was inserted in the file system, other times not. Within files individual letters and enclosures are often missing – in other words the numbers “skip.” Oversized maps or plans and often photographs were usually, but not always, removed and filed separately. However, they are usually noted on the document “map enclosure 110-19-4,” and as this same numerical system is used at the cartographic archives at College Park, often a map or plan may be found in Cartographics with this number. Photographs do not seem to have fared as well – the location of many remains a mystery.

Archives II, College Park, MD – c. 1917 – 1945

Archives II generally contains military records dating from the adoption of the War Department Decimal System, around the start of World War I. This system, whereby files are grouped by topic, described in more detail in a following section. While this facilitates research on particular topics, it means that files concerning different topics on a particular fort are not located together.

There are, however, exceptions to this classification system, most notably the Records of the Office of the Chief of Artillery/Coast Artillery, 1901 – 1917, in RG 177; the files of the Construction Division in the Records of the Office of the Chief of Engineers; and most importantly the harbor defense files in the Records of the Office of the Chief of Engineers. The first of these is arranged by file number, the last two alphabetically, either by fort name or harbor defense.

Whether in Archives I or II, keep in mind that the researchers who preceded you may not have put the records back exactly in their proper order. Before you conclude that a file or an enclosure does not exist, be sure to check the box to make sure it was not re-filed out of order.

Probably the most important records for coast artillery posts were those kept by the Corps of Engineers, who built and maintained the tactical structures – batteries, mine structures, fire control stations, searchlights, radar, and communications buildings. Because much of this involved detailed plans for weapons and fire control, the engineers routinely documented much of the decision-making process that led to the construction of the tactical structures. In addition, in December 1941, the Construction Division was transferred from the QMC to the Corps of Engineers, who took over responsibility for constructing and maintaining non-tactical structures. Because of this, many of the records of these buildings passed to the engineers, and are therefore filed in RG 77 rather than RG 92.

Archives I

The primary series of engineer records is Entry 103, General Correspondence, 1894 – 1924, arranged by file number. Entry 99 is the name and subject index cards.

Entry 220 is four boxes of binders on harbor defenses maintained in the Office of the Chief of Engineers. The binders, generally one for each harbor defense, contain a cumulative record of engineer activity at the forts until the early 1920s. This key resource should not be overlooked.

Entry 225 contains 15 boxes of miscellaneous papers dealing with harbor defense. The most important are numerous plans by the Board of Engineers for the artillery, mine, searchlight, and land defense of different harbor defenses. In addition, there are reports of completed batteries (RCBs) dating between 1910 and 1919 for most harbor defenses. See http://members.aol.com/vexillarii/Main.html for a listing of the contents of this entry.

Archives II

The key files of the Corps of Engineers dealing with fortification after WWI are arranged geographically in two entries, thankfully separate from the corps’ other records. Entries 1007 (classified) and 1009 (unclassified) contain the Harbor Defense Geographic Files. The most interesting files tend to be in 1007 (including the RCW files), but both entries should be searched carefully. The files are organized alphabetically by harbor defense, as listed in the RG 77 finding aids at Archives II.

Since the Construction Division and its responsibilities for non-tactical buildings and systems – barracks, water systems, wharves, etc… – was transferred to the Corps of Engineers in December 1941, the vast bulk of the records compiled and preserved by the QMC are now located in RG 77. There are two primary types of records. Entry 391 contains Construction Completion Reports, 1917 – 43. These often very detailed narrative reports of QMC construction or repair projects were submitted by constructing quartermasters. While they do not exist for all forts or all projects, they do contain a wealth of information on the projects that are covered, often including B&W photos. Entry 391 is arranged alphabetically, and the individual box numbers for each fort are shown in the finding aid.

Entries 393 and 394 contain the Historical Records of Buildings at army posts. The Coast Defense Journal, Vol. 16, No. 2 (May 2002), pp. 29 – 42, describes these forms in more detail – they are large cards or sheets with data on each non-tactical building, usually with a photograph and often a floor plan. These are the best single source for non-tactical structures. Entry 393 covers posts still active in 1942, while Entry 394 covers those abandoned by that date. The files are arranged alphabetically by fort, and the finding aid lists the boxes for each fort.

Record Group 92 – Office of the Quartermaster General

The QM Corps (QM Department before 1912) were responsible for non-tactical building construction before December 1941, as well as functions analogous to public utilities, such as roads, fences, wharves, water and electric supply, as well as transportation and provision of uniforms, food, and fuel. Many of these records are vital to understanding the history of the forts and of structures such as barracks. All types of watercraft were also an important quartermaster function.

Archives I

Entry 89 contains correspondence, 1890 – 1914, by file number. Entry 88 contains the record cards and Entry 84 the name and subject index to Entry 89. These documents relate to the wide range of quartermaster responsibilities.
Record Group 94 – Adjutant General’s Office

The Adjutant General’s Office was the record keeper for the army, as well as managing a number of specific functions, such as personnel. Because they kept records of much military correspondence, the AGO files are relatively large.

Archives I

Entry 25 contains correspondence between 1890 and 1917, arranged by file number. Entry 27 contains the name and subject index cards. Entry 61 contains the Returns of Army Departments, 1818 – 1916. Entry 66 contains Returns of Military Organizations, from the “early 1800s” to 1916. An interesting series is Entry 280, the reports of the National Land Defense Board, 1907 – 1915. Entry 281 is the index to Entry 280.

Record Group 407 – Adjutant General’s Office, 1917 – Present

Archives II

The records of the Office of the Adjutant General after 1917 are contained in Record Group 407, at Archives II. The “Central Decimal Files” are in Entry 37, which is divided into eight entries by letter suffixes, such as 37H, which contains classified and unclassified correspondence between 1926 and 1939. Other entries in the 37 series are for different dates, for bulky files, and in some cases for separating classified and unclassified files. These entries are arranged by the decimal system, but decimal file 662, “Gun and Mortar Batteries,” is subdivided by location, and may contain numerous documents, some of which are duplicated in other record groups and some of which are not. The interwar correspondence of the War Plans Division found here is particularly interesting.

Harbor defense annexes and supplements of the 1930s and 40s are filed in several places, but the most complete set is found in Entry 366, filed alphabetically. The box numbers for each harbor defense are shown in the finding aid.
Record Group 156 – Office of the Chief of Ordnance

These records, by their nature, are not primarily arranged by location. However, by use of the indexes, files relating to specific forts or harbor defenses can be found.

Archives I

The primary source for the Endicott-Taft era is Entry 28, correspondence between 1894 and 1913, which is arranged by file number. A smaller series, Entry 29, contains additional correspondence between 1910 and 1915. Entry 26 contains the name and subject index to Entry 28 and some of Entry 29. Entry 34 indexes the portion of Entry 29 between 1912 and 1915; however, it is located at Archives II. Appendix I to the archives finding aid has an abbreviated file number list. While only a small portion of the total files are represented, it is a good place to start compiling interesting numbers to have pulled, and may save an entire call cycle at the reference room. Most master file numbers for coast artillery forts seem to be listed in this finding aid.

Archives II

Entry 36 contains general correspondence between 1915 and 1941. Entry 39 is smaller and contains confidential correspondence between 1917 and 1940. Like other records of the period, these entries are arranged in the War Department Decimal System, by subject rather than by location. Entry 34 contains the name and subject indexes to Entry 36 in three subseries, divided by date. Entry 38 contains the name and subject index to Entry 39.

RG 156 (Records of the Chief of Ordnance), Entry 712, at Archives II, College Park, MD, consists of 13 boxes of 3 x 5 cards. Each seacoast gun and carriage has a separate card, filed by model and serial number. In addition, many other pieces of equipment also have cards. The last entries on the cards were made around 1946.

The Ordnance Department tracked the location and/or disposition of each gun and carriage. The omissions, if any, are few. (The cards include those for a number of one-of-a-kind items, such as the 10-inch breechloading mortar, along with equipment from plotting and ammunition cars to star gauges.) The cards are organized by size and model year, often subdivided by manufacturer. Items that had been modified are usually filed separately; for instance, M1895 guns are separate from M1895MIs, while M1895A1s and M1895MIA1s are filed together. Much space is devoted to railway guns, carriages, and such equipment, as well as a large number of trench mortars. Other cards seem to indicate the numbers of certain items ordered during 1941 or 1942, and there are cards filed by harbor defense, which seem to show what remained in 1946.

As always, the accuracy is not guaranteed. There was much correspondence between the Ordnance Office and the forts, discussing the serial numbers and model designations of various pieces of ordnance. It seems, however, that the Ordnance Office records usually proved correct. In a minority of instances, the first date on the card is July 1, 1917, which seems to reflect the date the particular cards were started, rather than the date the item was acquired.

The cards show the locations and movements of the items, but with little or no comment on the reasons behind the moves. A card may note that a gun was shipped from Fort Monroe to Watervliet Arsenal, but not indicate why. In other instances, especially when a gun was relined, the card may contain a brief notation to this effect.

The Ordnance Department devoted many man-hours to maintaining this file, and it is still invaluable for tracking specific pieces of ordnance or resolving discrepancies on RCWs.

Record Group 165 – War Department Special Staffs and Boards
Archives I

Entry 165 has the records of special army boards, usually those containing representatives of more than one department. Entries 518 and 519 hold the correspondence of the Board to Revise the Report of the Endicott Board (the Taft Board), 1905 – 1906. While much is of a general nature, specific proposals and recommendation for individual harbor defenses are in these holdings. For the Endicott Board, similar records are in RG 77, Entry 485. For both the RG 77 and RG 165 records the entries are small (only a few inches of material), so it is best to just request the entire entry and look for the harbor of interest rather than try to locate a finding aid.

Record Group 177 – Offices of the Chiefs of Arms
Archives II

The general correspondence records of the Office of the Chief of Artillery (1901 – 1907) and Chief of Coast Artillery (1907 – 1918) are arranged by file number in Entry 4, with subject index cards in Entry 1. In addition, a file-by-file list of the contents, searchable by computer, with box numbers, has been prepared. Anyone interested can request it by email at bollingsmith@hotmail.com. There are separate files for fire control, submarine mining, and artillery defense plans for most harbor defenses, as well as other files specific to particular locations.

The correspondence of the Office of the Chief of Coast Artillery after approximately 1918 is in Entry 8, arranged in the War Department Decimal System. Entry 7 contains the alphabetical index to Entry 8. Of particular interest in Entry 8 are the inspection reports filed between decimal 333 and 333.14. These contain a number of different types of reports, but each category is filed by harbor defense, and they constitute a valuable record.

There is considerable overlap between different decimal files, and in some cases, different levels of command filed the same inspection under different decimal file numbers. Each decimal file, in turn, is divided into files for each harbor defense, which were assigned numbers in alphabetical order. For instance, /15 indicates reports for the HD of Manila and Subic Bay. In addition to the designated harbor defenses and forts, reports are included for some Army Reserve and National Guard regiments, as well as for some corps area reserve components. \

In general, these inspections are divided into five groups, decimal file numbers 333, 333.1, 333.12, 333.13, and 333.14.

Decimal file 333 is relatively thin and largely contains the results of “annual surveys” by higher commands. These often mention the inspection only briefly, with excerpts of particularly significant findings and some descriptions of corrective action taken.

Decimal file 333.1 includes overall annual inspections by the chief of coast artillery, departmental (later corps area) and coast artillery district commanders, and their staff, to include the Inspector General’s Department. These cover a wide range of topics, from appearance of personnel to condition of buildings and materiel to shoefitting tests. Recommendations could be as significant as that recommending that Fort Greble, RI, be disposed of. (The recommendation was not approved.)

Decimal file 333.12 deals largely with tactical inspections by coast artillery district commanders. Considerable emphasis was placed on tactical problems used for training exercises in the harbor defenses. Also included in this file are technical inspections, which concentrated on tactical equipment. Some inspections under this file were excruciatingly detailed, such as one 1919 inspection of Fort Kamehameha, which cited with disapproval, among many other things, “1 man with safety pin on shirt to replace button,” and “Company Commander saluted inspector.”

Decimal file 333.13 includes training inspections. These evaluated training programs, both for assigned units and for such outside units as ROTC, CMTC, National Guard, and Organized Reserve. In a few instances (Manila and Subic Bays, 1931), inspections in this file are essentially tactical.

Decimal file 333.14 contains the largest groupings, the Signal Corps inspections. These annual inspections contained a detailed narrative report and a lengthy (often more than 20-page) form listing EVERY single Signal Corps item on the post. Items such as telephones are listed, as are hand tools, tacks, and even, in one instance, a teakettle. The full form was not filled out every year; inspectors were allowed to submit only the pages with changes. In general, the entire form was usually filled out around every five years, while the number of pages submitted in the intervening years varied considerably. The post commander submitted his response to the inspection report, as did everyone in the chain of command.

When a commander or an inspector recommended changes or additional equipment, the correspondence could be lengthy, although often ending with the statement that no money was available. These reports describe the actual condition of the coast defense communications systems, and are a useful antidote to manuals that only describe the ideal systems. Obviously, these are of particular value to those interested in technical equipment.

War Department Decimal File System
Bolling Smith

Just before World War I, the army adopted a decimal system for its files. The initial manual was published 1914, based on the Dewey Decimal System then in use for libraries. Although some changes were made, in general the system remained relatively consistent. The 1943 edition of the War Department Decimal File System, which replaced the editions of 1914 and 1918, is over 400 pages, including listings and index, and contains the clear statement “THE ADDITION OF NEW NUMBERS OR DECIMAL SUBDIVISIONS IS PROHIBITED.” (Emphasis in the original). Decimal subdivisions other than those in the 1943 manual do exist in earlier files, and probably in later ones also. For example, radar was not even mentioned in the 1943 edition.

Classification of documents was subjective. Different departments might classify documents differently depending on their particular interests, or perhaps simply depending on who made the classification. Also, documents might contain subject matter relevant to several classifications. The archives contain many cards indicating documents had been refiled under different numbers.
Nonetheless, a general description of the system may be of some assistance to researchers. Files were divided into nine general classes:

000-General
100-Finance and accounting
200-Personnel
300-Administration
400-Supplies, services, and equipment
500-Transportation
600-Buildings and grounds
700-Medicine, hygiene, and sanitation
800-Rivers, harbors, and waterways

The alphabetical index to the 1943 edition is 301 pages long, and relatively complete (“white mice…454.7”). Those interested in earlier files may wish to consult an earlier edition, as some numbers were changed. The listings below from the 1943 edition pertain to coast defense. In general, references to subjects not related to coast defense have been deleted.

320: ORGANIZATION OF THE ARMY
321-ARMS OF SERVICE AND DEPARTMENTS (Organization and reorganization, duties, functions, policies, etc.) (Coast Artillery Corps, etc.)
322-ORGANIZATIONS AND TACTICAL UNITS (Regiments, batteries, commands, etc.)
323-GEOGRAPHICAL DIVISIONS
323.3-Military departments and divisions (forts, etc.)
353-TRAINING
353.1-Target practice
353.4-Firing (Ballistics, circuits for seacoast, proof firing, salvos and salvo points, etc.)
370: EMPLOYMENT, OPERATION, AND MOVEMENT OF TROOPS
370.3-Land and marine tactics
370.31-Submarine mine defense
370.32-Harbor and coast defense
453-RAILWAY EQUIPMENT
453.1-Railway cars for guns
453.2-Railway cars for howitzers or mortars
470: AMMUNITION, ARMAMENT, AND OTHER SIMILAR STORES
470.2-Dummy armament (drill cartridges, dummy cannon, carriages, cartridges, powder bags, projectiles, etc.)
470.3-Searchlights and outfits
470.4-Turrets
470.5-Armor plate and navy armor.
471-AMMUNITION
471.3-For seacoast guns
471.31-parts and accessories. (Accessories, balancer sets, cable, carbons, clutches, controllers, curtains, mirrors of glass or metal obturators, projectors, shutters, stops, etc.)
471.5-Powder and powder charges. (6-pounder-16-inch gun; maneuver, smokeless, black, saluting, igniting, and shrapnel powder, etc.)
471.8-Parts and accessories
471.81 Components. (Bands and caps for projectiles, covers, plungers, tracers, etc.)
471.82-Fuzes, adapters, and boosters
471.83-Primers
471.87-Containers for ammunition.
471.88-Ammunition service
471.9-Miscellaneous
471.93-Ammunition for antiaircraft guns.
471.942-Rockets for antiaircraft guns.
472-CANNONS OR GUNS
472.1-Mobile guns (Subcaliber, siege guns, 12 and 16-inch guns, and over.)
472.2-Howitzers (12 and 16-inch, and over.)
472.3-Seacoast guns (Subcaliber, and 3 to 16-inch, and over)
472.4-Mortars
472.5-Automatic and machineguns.
472.6-Navy guns for submarine chasers and other purposes.
472.8-Parts and accessories.
472.81 Parts (Blocks, breech mechanisms, castings and forgings, firing mechanisms, hoops, jackets, lanyards, safety devices, sleeves, tubes, etc.)
472.82.Accessories (Cleaning devices, covers, rammers, sights, sponges, staves, subtarget gun machines, etc.)
472.9-Miscellaneous cannon
472.93-Antiaircraft guns
473-CARRIAGES, MOUNTS, AND TRIPODS
473.1-For mobile guns
473.2-For howitzers
473.3-For seacoast guns
473.4-Mortar carriages
473.5-Mounts for machine guns.
473.6-Mounts for navy guns.
473.8-Parts and accessories.
473.81-Fixed parts (base ring, chassis, cradle, scales, shields, top carriage, racer, etc.)
473.82-Mechanisms
473.83-Electrical equipment, circuits, conduits, magnetos, telephone, terminal boxes, wiring, etc.
473.84-Spare parts.
473.85-Sights for carriages
473.86-Caissons, covers, limbers, etc.
473.864-Observation towers.
473.865-Covers for carriages.
473.866-Platforms, etc.
473.87-Braces and brackets for firing materials, fuze setters, lamps, range finders, sights, telautographs, telephones, etc.
473.88-Carriers and containers (armament chests, gun carriages, howitzer carriages, mortar carriages, etc.)
473.9-Carriages for miscellaneous guns (For antiaircraft guns, subcaliber guns, etc.)
476-LAND AND SUBMARINE MINES AND EQUIPMENT.
476.1-Equipment for mining
476.2-Cables and equipment
476.3-Supplies and tools (Boat telephones, cable cutters, drying ovens, supply list, etc.)
477-SUBMARINE NETS AND SIMILAR APPLIANCES (Anti-submarine devices, automatic torpedo destroyers, destroyers, etc.)
600: BUILDINGS AND GROUNDS
600.05-Name or designation; naming (Naming posts)
620: BARRACKS AND QUARTERS
621-BARRACKS FOR ENLISTED MEN
623-QUARTERS FOR NONCOMMISSIONED OFFICERS
625-QUARTERS FOR COMMISSIONED OFFICERS
630: POST BUILDINGS
631-ADMINISTRATION, DRILL, AND RECREATION BUILDINGS
660: FORTIFICATIONS
660.1-Foreign
660.2-Coast and antiaircraft defense, and land defense works
660.3-Defense sea areas, mine areas.
660.4-Protective installations (Bombproofing, gasproofing, etc.)
661-FIELD FORTIFICATIONS
662-GUN AND MORTAR BATTERIES
663-MINE STRUCTURES
664-CABLE STRUCTURES
665-FIRE CONTROL INSTALLATIONS
665.01-Reports on, reports and progress.
665.02-Fire control diagrams
665.1-Stations.
665.11-Field of view from
665.12-Protection for
665.2-Commanders’ and other stations
666-SEARCHLIGHT STRUCTURES