This is a style guide for military history articles. It is intended to provide editors working on such articles with recommendations in relation to article naming conventions, formatting and presentation, template use, and categories. Advice on notability and content in relation to military history articles can be found at Wikipedia:WikiProject Military history/Notability guide and Wikipedia:WikiProject Military history/Content guide.
Many articles may deal extensively, but not exclusively with military-related topics. When in doubt, or when there is no clear consensus, defer to WP:MOS. As a general rule, this guidance should only be used where it is helpful, and should not be used as grounds for extensive disruptive renovations of existing articles.
Biographies
Consensus to follow this guidance on biographies of living or deceased persons should be based primarily on the prominence of military service in the WP:NOTABILITY of the individual. For example, an article on a Medal of Honor or Victoria Cross recipient, who is notable only for their military service, should most likely follow this guidance. An article on an individual, such as Elvis Presley, who would be notable had they never served in the military, most likely should not. Biographies of civilians, such as Marise Payne or Ash Carter, who are notable in large part for military-related reasons, but who themselves did not serve in uniform, should generally not follow this guidance.
Biographies of living people (BLPs) and those of people who have recently died must follow Wikipedia's BLP policy.
An article should generally be placed at the most common name used to refer to the event (such as Battle of Gettysburg, siege of Leningrad, attack on Pearl Harbor, or Doolittle Raid). If there is no common name, the name should be a descriptive geographic term such as "battle of X" or "siege of Y", where X and Y are the locations of the operations; see also the section on capitalization. Non-neutral terms such as "attack", "slaughter", "massacre", "raid", "liberation", or "fall" should be used with care.
Name of military event/organisation order of battle
For the common case where the orders of battle for a military event are split into separate list articles by belligerent or opposing forces, then the naming conventions for split lists apply, and the format becomes:
Name of military event order of battle: Belligerent
Operational codenames generally make poor titles, as the codename gives no indication of when or where the action took place and only represents one side's planning (potentially leading writers to focus on that side's point of view). It is better to use an appropriate geographical name for the article, creating a redirect from the operational name, for all but the most well-known operations (such as Operation Barbarossa), or for military actions that were never carried out (such as Operation Green).
References to operations are to be in accordance with the following examples, noting the use of capitals in the examples.
The Axis plan, Operation Xyz, was a proposal for the invasion of ...
The Xyz operation called for a combined overland and amphibious ....
Troop movements in preparation for Xyz commenced in ...
Operation Xyz is a compound proper noun and capitalised accordingly. No emphasis, such as quote marks, boldface (see special case, below) or italics are added even in the case of non-English words such as the following. A distinction is made when the correct non-English name or a translation is being offered.
Operation Rimau
Operation Barbarossa (ألمانية: Fall Barbarossa, literally 'Case Barbarossa')
Operation Wunderland (ألمانية: Unternehmen Wunderland)
Links to articles in a campaign box are to be italicised but are not preceded by the word 'Operation' – i.e. "Cartwheel" only. Refer to the example in the Solomon Island campaign box for an actual example.
Boldface is used to highlight the first occurrence of the title word in the lead section in accordance with MOS format of the first sentence (lead). It is also used (almost exclusively in the lead) when the operation name is a redirect to a page about the associated battle or an alternative (synonymous or nearly synonymous) name for the operation as in the examples that follow
For the article, Normandy landings, the lead opens: Normandy landings (codenamed Operation Neptune) were the landing operations on 6 June 1944 ...
For the article, Operation Torch, the lead opens: Operation Torch (initially called Operation Gymnast) was the ...
Tanks
This section is the subject of a current discussion. Please feel free to join in. This doesn't mean that you may not be bold in editing this section, but that it would be a good idea to check the discussion first.
For the sake of uniformity, ease of understanding and clarity, all articles documenting tanks should include "tank" as a part of its title, generally appended at the end.[1] For instance:
An article about a unit, formation, or base should be placed at "Name" or if "Name" is ambiguous at "Name (disambiguating term)". The name should generally be either the official name used by the armed forces to which the unit or base belongs; or, in cases where no relevant formal name exists or where a formal name is not commonly employed by historians, the most common name used in historical literature.
A name originally in a language other than English should be adapted by translating common terms (such as designations of size and type) and transliterating the remainder of the name. The choice of which components of the name are to be translated (and how) should follow the conventions employed by reputable historical works on the topic; some collected recommendations for specific terms are maintained by the relevant national task forces. The original name should be provided in the first sentence of the article, following the translated name; for example: The 3rd Mountain Division (3. Gebirgs-Division) was... or Boden Fortress (سويدية: Bodens fästning) is....
Names should generally follow the stylistic conventions used by the service or country of origin. For example, while US and British usage has spelled-out numerals for army-level formations and Roman numerals for corps, editors writing about different countries should follow those countries' normal usages; thus, "3. Panzer Armee" becomes "3rd Panzer Army", and "18-ya Armiya" becomes "18th Army".
For units the names of which are ambiguous on Wikipedia, the disambiguating term should be the common name of the country the unit belongs to (as in 4th Infantry Division (United Kingdom)), or, if such usage is still ambiguous (or where the unit does not serve a country), the name of the service branch to which the unit belongs (as in 1st Panzer Division (Wehrmacht)). The disambiguating term is not necessary in cases where the name is unambiguous (as in The Queen's Own Rifles of Canada or Preobrazhensky regiment).
In cases where a unit's name can reasonably be expected to be used by multiple armed forces—particularly in the case of numerical unit designations—the units should generally be preemptively disambiguated when the article is created, without waiting for the appearance of a second article on an identically named unit. If this is done, the non-disambiguated version of the unit name should be created as a disambiguation page (or a redirect to the disambiguated version).
For bases the names of which are ambiguous on Wikipedia, the disambiguating term should be the region, province, state, or territory in which the base or fortress is located; for example, "Fort Lyon (Virginia)" and "Fort Lyon (Colorado)". The disambiguating is not necessary in cases where the name is unique to a single fortress or base.
When a unit or base has had multiple names over the course of its existence, the title should generally be the last name used; however, exceptions can be made in cases where the subject is clearly more commonly known by one of the previous names.
Root pages for the armed forces of a state are named, if the official name is known, by the official name's English translation (for example, "Australian Defence Force"). If the native language name is most commonly used, this should be kept (for example, "Bundeswehr"). Other national armed forces are only provisionally located at "Military of X", and should be renamed to the translation of the official name when available. Alternately, articles can be renamed if there is consensus over how the armed forces in question are normally referred to in common usage (for example, "United States Armed Forces").
A number of naming conventions exist specifically for category names; most of these are used to ensure consistent naming among all the sub-categories of a particular category.
"X by country"
In most cases, sub-categories of a category named "X by country" take names of the form "X of [the] Y", where Y is the most common name of the country in question. For example:
In most cases, sub-categories of a category named "X by period" take names of the form "X of the Y period", where Y is the name of the period of warfare in question. For example:
In most cases, sub-categories of a category named "X by war" take names of the form "X of [the] Y", where Y is the most common name of the war in question. For example:
Note that this form of category tree tends to exhibit more varied naming than the others. For example, Category:Battles by type also includes the non-standard Category:Sieges (since "Siege battles" would be a cumbersome name).
Intersection categories
The names of intersection categories generally follow the same conventions as above, with the name components of their parent categories placed in normal grammatical order (usually with period/war designations given after country/branch ones). This produces, for example, "Naval battles of the Early Modern period" (type and period) and "Airborne regiments of the United States Army in World War II" (type, size, branch, and war).
The general rule from MOS:CAPS is that wherever a military term is an accepted proper name, as evidenced by consistent capitalization in reliable sources, it should be capitalized in Wikipedia. Where there is uncertainty as to whether a term is a proper name, consensus should be reached on the talk page; the MOS:CAPS default is to use lower case, unless and until evidence of consistent capitalization in the sources is presented.
When using a numerical model designation, the words following the designation should be left uncapitalized (for example, "M16 rifle" or "M6 bomb service truck") unless it is a proper noun (for example, M1 Abrams).
Existing articles related to military history should follow MOS:DATERET as a default, and extensive efforts should not be undertaken to comply with this guidance for its own sake, unless there is strong consensus for the change.
Per MOS:DATETIES, articles on subjects predominately related to militaries or military history should use the standard format adopted by the United Nations:[2] DD Month YYYY (or D Month YYYY). This includes spaces and excludes hyphens or commas. In cases where the day is a single digit, a leading 0 should be omitted. For example:
1 January 1900 and not 1-January-1900; 1 January, 1900; 1January1900 or 1, January 1900
1 January 1900 and not 01 January 1900
All articles should follow MOS:DATEUNIFY, and should not mix date formats.
En dashes
The Manual of Style specifies that an en dash rather than a hyphen should be used. Where there are internal spaces within one or both items, the en dash should be spaced on both sides. Examples:
1968–1970, not the hyphenated 1968-1970
May–August 1944
3 June – 15 August 1914; not 3 June - 15 August 1914
12–14 September 1943
Minimal repetition
Consider expressing date ranges without repetition; thus:
January–March 1968, not January 1968 – March 1968
3–4 November 1951 not 3 November 1951 – 4 November 1951; nor even 3 November – 4 November 1951
Closing item
It is preferred that the closing year in a year range be four digits rather than two, per MOS:DATERANGE:
The second phase (2004–2006), rather than The second phase (2004–06)
In general, the use of flag icons is not recommended but the Wikipedia:Manual of Style (flags) acknowledges that it may be appropriate to use flags when summarizing military conflicts in an infobox. Nonetheless, flag icons should only be inserted in infoboxes in those cases where they convey information in addition to the text. When deciding whether flag icons are appropriate in a particular context, consider:
Do the icons convey useful information to the reader, or are they merely decorative? Icons that differentiate among several parties (for example, icons used to indicate commander allegiance in Battle of the Atlantic) are likely to be useful, while icons that convey irrelevant or redundant information are usually not.
Can flag icons be used consistently? In other words, do all the groups in a given list have usable flags? If only a few have them, it may be better to omit flags for all the items than to have a different layout for each one.
Will adding icons disrupt the existing structure or flow of the text? It is important to keep in mind that infobox templates permit limited useful width, so the use of flag icons in them can potentially conflict with readability.
When flag icons are used, they should be historically accurate ones. In particular:
When dealing with items related to a particular time period, avoid using anachronistic flags from other time periods. Be especially careful to avoid using the flags of modern countries for ancient ones; in many cases, the proper successor of a country no longer in existence is a matter of considerable controversy.
Avoid using national flags in inappropriate contexts, such as for groups or individuals not aligned with any country.
When dealing with biographical infobox templates, the most common practice is to use flag icons to indicate allegiance or branch of service, but not place of birth or death. However, there remains considerable disagreement regarding the appropriateness of flags in such cases, so editors should not regard this as a universal rule.
In general, articles should strive to be precise. Where the names of specific operations, formations, or commanders are available, for example, it is usually better to use them instead of more general terms; "The Ninth United States Army would launch an offensive, codenamed Operation Grenade, across the Roer" is likely to be more helpful to the reader than "The United States would launch an offensive across the Roer".
It is important to note, however, that the level of precision in an article should be appropriate for its scope. Articles dealing with narrower and more specialized topics can use more specific terminology than may be feasible in articles dealing with broad overviews or very general topics; and general terminology is often appropriate in an introductory section even where more specific terms are used in the body of the article. Precision should not be pursued to such an extent that it impairs the average reader's understanding of the topic.
Overly lengthy continuous blocks of text should be avoided; sections which are so long as to impede reader understanding should be broken down into subsections. There remains some disagreement regarding the precise point at which a section becomes too long, so editors are encouraged to use their own judgment on the matter.
Policy requires that articles reference only reliable sources; however, this is a minimal condition, rather than a final goal. With the exception of certain recent topics that have not yet become the subject of extensive secondary analysis, and for which a lower standard may be temporarily permitted, articles on military history should aim to be based primarily on published secondary works by reputable historians. The use of high-quality primary sources is also appropriate, but care should be taken to use them correctly, without straying into original research. Editors are encouraged to extensively survey the available literature—and, in particular, any available historiographic commentary—regarding an article's topic in order to identify every source considered to be authoritative or significant; these sources should, if possible, be directly consulted when writing the article.
Articles that report on "black projects" and other classified topics are required to fully conform to Wikipedia's policies governing verifiability, original research, and fringe theories. All information presented in such articles must be appropriately cited to reliable sources as outlined above. The inadequacy of public sources may not be used to justify the inclusion of unsourced or poorly sourced material in an article or to relax normal standards of sourcing and citation.
The nature of historical material requires that articles be thoroughly—even exhaustively—cited. At a minimum, the following all require direct citation:
Direct quotations of outside material
Paraphrasing or other borrowing of ideas from an outside source
Controversial or disputed statements
Subjective or qualitative judgments
Numerical quantities or statistics
In general, any statement for which a citation has been explicitly requested by another editor should be provided with one as well.
Beyond this, editors are encouraged to cite any statement that is obscure or difficult to find in the available sources, as well as any significant statement in general. There is no numerical requirement for a particular density of citations or for some predetermined number of citations in an article; editors are expected to use their best judgment as to how much citation is appropriate. When in doubt, cite; additional citations are harmless at worst, and will prove invaluable in the long term as one moves toward featured article status.
In general, articles should use footnotes. A number of different formatting styles are available; so long as an article is internally consistent, the choice of which to use is left to the discretion of the major editors. Discursive notes are usually separated from reference citations (as here and here), but the two types are sometimes combined (as here). A single footnote may be used to provide citations for any amount of material; while they typically apply to one or a few sentences, they may also cover entire paragraphs or sections of text. In cases where the connection between the citations and the material cited is not obvious, it is helpful to describe it explicitly (for example, "For the details of the operation, see Smith, First Book, 143–188, and Jones, Another Book, chapters 2–7; for the international reaction, see Thomas, Yet Another Book, 122–191").
Requesting citations
Editors should take a reasonable approach when requesting citations. Unless the accuracy of a statement is in significant doubt, it is generally better to start with a request for citations on the article's talk page, rather than by inserting {{fact}} tags—particularly large numbers of such tags—into the article. Over-tagging should be avoided; if a large portion of the article is uncited, adding an {{unreferenced}} or {{citation style}} tag to an entire section is usually more helpful than simply placing {{fact}} tags on every sentence. Note that some articles contain per-paragraph citations, so checking the citations at the end of a paragraph may yield information about facts or figures in the paragraph as a whole.
Templates
The various primary and auxiliary infobox templates and navigation templates maintained by the Military history WikiProject are all coded to use a common set of styling characteristics. This is needed primarily because a number of the templates are designed to be stacked together to present the appearance of a continuous block; it is also beneficial for providing a consistent appearance to the entire set of articles within our scope.
A few general guidelines apply to all military history infoboxes:
Most of the fields in each infobox can be omitted if desired; the choice of which ones are appropriate for a particular article is left to the discretion of the article's editors.
Multiple values given in a single field should be separated by both commas and, where appropriate, line breaks; merely spacing them onto separate lines can confuse screen reader software, and is ambiguous when long terms wrap onto multiple lines in their own right.
A primary infobox is intended to provide a summary table for some topic. It should generally be placed at the top of an article, before the lead section; this will cause it to be displayed in the top right corner. Documentation may give advice on the appropriate way to populate parameters and should be followed.
Used for all conflicts and combat operations, such as battles, campaigns, and wars. The "result" parameter has often been a source of contention. Particular attention should be given to the advice therein. The infobox does not have the scope to reflect nuances, and should be restricted to "X victory" or "Inconclusive". Where the result does not accurately fit with these restrictions use "See aftermath" (or similar) to direct the reader to a section where the result is discussed. In particular, terms like "Pyrrhic victory" or "decisive victory" are inappropriate for outcomes. It may also be appropriate to omit the "result".
An auxiliary infobox is a supplementary template intended to be used in conjunction with one of the primary infoboxes; it is usually placed directly below the primary infobox, but other layouts are possile. It is common for multiple auxiliary infoboxes to be used on a single article.
The various navigation templates maintained by the Military history WikiProject are all intended to be implemented through a single base template, which combines the project's common template style with the standard navigation box format. This is needed primarily to allow multiple such templates to be stacked together—with each other, or with infobox templates—to present the appearance of a continuous block; it is also beneficial for providing a consistent appearance to the entire set of articles within our scope.
Any military-related navigational template should be created using the {{military navigation}} base template, as shown below:
The actual page name (i.e. "XYZ" for Template:XYZ) of the newly-created template.
title
The displayed title of the navigation box.
listclass
Optional – but typically hlist, to format content as horizontal lists. In the case of hlists in above or below fields, set bodyclass=hlist, instead.
style
Optional – an alternative style for the template; this may be set to "wide" to produce a full-width box. The alternative style should be used sparingly; it is intended that the majority of navigational templates will use the default style (in the wild, "wide" has become quite common). The above example template formatted with style=wide is shown below:
Optional – may be set to "collapsed" to force the template to render in its closed state by default.
odd_color/even_color
Optional – the stripe colors for alternating listN items to use. These parameters should be used sparingly; in the absence of a good reason to do otherwise, templates should use the default stripe colors.
groupN/listN
The body of the navigation box, consisting of successive horizontal blocks of content (the listN fields) with optional labels (the corresponding groupN fields). Please see the documentation for {{navbox}} for more details on the different layouts possible.
above
Optional – the sub-header of the navigation box; please see the documentation for {{navbox}} for more details on the resulting layout when this is used.
below
Optional – the footer of the navigation box; please see the documentation for {{navbox}} for more details on the resulting layout when this is used.
image
Optional – an image to be displayed at the right of the box, given in the form [[Image:Example.jpg|100px]]. This parameter should be used sparingly, and typically only in conjunction with the full-width template style.
imageleft
Optional – an image to be displayed at the left of the box, given in the form [[Image:Example.jpg|100px]]. This parameter should be used sparingly, and typically only in conjunction with the full-width template style.
If several infoboxes or navigation templates are stacked along the right margin of an article, the [edit] links of nearby sections may be moved to unexpected positions. A number of workarounds exist; full details are available on the linked page.
Shifted header wrapping
A long header used in a narrow navigation template may wrap incorrectly, with the second line being indented further than necessary. A workaround is possible by adding a <br /> tag between the words where the wrapping is to occur. This should be done to separate link-text to the right of the 'pipe' (|), as follows: [[Article title|Article <br /> title]]. An alternative method is to use {{allow wrap}} for the link-text as follows: [[A very long article title|{{allow wrap|A very long article title}}]], which allows the browser to break as-needed.
Stretching or overflowed boxes
A very long header formatted as a single link may cause a template to stretch beyond its normal width, or the whole link to extend off too far to the right. A workaround is possible by breaking the header onto multiple lines, as shown above.
A "campaignbox" is a type of navigation template that contains links to articles about the battles in a particular campaign, front, theater or war. See the template documentation for details.
The category scheme originates in two root categories—Category:War and Category:Military—and can be thought of as two tree structures that intersect at several points. A guide to the top-level sub-categories of these two root categories is presented below; for brevity, a number of categories that are rarely used or lie outside the scope of this project have been omitted.
In general, articles and categories should be placed in the most specific applicable categories, and should not be placed directly in a "parent" category if they are already present in one of its sub-categories. In other words, if an article is placed in Category:Wars involving the United States, there is no need to place it in Category:Military history of the United States as well.
In some cases, entire category trees will nest as above. For example, all "by war" categories should be sub-categories of the applicable "by period" category, and that a redundant "by period" label should not be applied to articles where a "by war" one is given (for example, Category:Military units and formations of the Crusades should be a sub-category of Category:Military units and formations of the Middle Ages, so an article already in the first need not be added to the second).
Note that this strategy should be applied only when every article in one category belongs in the other. For example, it is inappropriate to make Category:Battles of the Napoleonic Wars a sub-category of Category:Battles involving the United Kingdom, because there are many battles in the first category in which the United Kingdom was not a participant; thus, Battle of Waterloo must include both categories separately.
In many cases, articles can be categorized through several parallel classification schemes, associating them with the related countries, wars, periods, and other topics. There are two general ways of applying multiple categories from these classification schemes to a particular article. The simplest, which can be sufficient for unusual combinations or small categories, is to apply each category separately. For example, a medieval French unit could be placed in both Category:Military units and formations of the Middle Ages and Category:Military units and formations of France. However, this system is unwieldy as category sizes increase; thus, common combinations of multiple categories can be made explicit by creating an "intersection" sub-category for them; for example, Category:Military units and formations of France in the Middle Ages.
A particular country will thus have a tree of categories containing every operation in which it participated. At its greatest extent, the tree will take a form similar to this:
Note that, particularly for countries the military histories of which do not include the modern period, many of these categories may be omitted. In particular, it is common for the "Battles involving Foo" and "Wars involving Foo" categories to be placed in the corresponding "Military history of Foo" category directly, without a separate "Military operations involving Foo" category between them.
Specific conflicts are typically classified as battles, campaigns, or wars for the purposes of categorization. In this context, the terms are generally understood to mean the following:
A war is a conflict bounded by periods (however brief) during which the combatants are formally at peace with one another; it generally consists of multiple distinct component operations such as battles or campaigns.
A campaign is a coherent series of smaller operations with a defined overall goal; this goal may, however, change over the course of the campaign.
A battle is a single, distinct engagement generally limited to a narrow geographic scope and typically characterized by the opposing forces encountering one another, engaging in some form of combat, and then separating.
In general, articles should be classified according to what the topic actually is, regardless of the name used. For example, a series of engagements generally regarded by historians as a campaign should be categorized as one even if it's referred to as the "Battle of X".
Some operations and conflicts may need to be classified into more than one of the above levels; however, this should generally be done only when it substantially adds to a reader's understanding of the events. The possible double-classification scenarios are outlined below:
War and campaign: This can occur when a "sub-war" is fought as part of a larger war (for example, the French and Indian War, as part of the Seven Years' War). A subsidiary conflict is typically a "sub-war" when it includes some participants not involved in the larger conflict; the article can then be categorized as a war involving those participants, but as a campaign involving the participants of the larger conflict.
Campaign and battle: This can occur in modern warfare, where a long-term engagement has been treated by historians as either a single battle or a sequence of separate battles.
War and battle: This should generally be avoided, except in the few cases where a war consisted of a single large battle and only a single article covers the conflict.
Some larger wars have dedicated categories (such as Category:Hundred Years' War). In this case, it is sufficient to categorize the war category as above; the war article (Hundred Years' War, in this example) need only be placed in the associated war category.
Articles about campaigns are usually placed in three sets of categories nested under Category:Military campaigns:
By date: a campaign article should always be placed in a category by year (such as Category:Conflicts in 1878) corresponding to the period during which it took place. Longer campaigns spanning several years may be placed in multiple year categories, or in the corresponding decade or century categories in extreme cases.
By war: a campaign article may optionally be placed in a sub-category of Category:Campaigns by war; this should generally be done only for wars that have a substantial number of campaign articles.
By participants: a campaign article should generally be placed in one or more sub-categories of Category:Military campaigns by country corresponding to the parties involved in the campaign.
Articles about battles are usually placed in four sets of categories nested under Category:Battles:
By date: a battle article should always be placed in a category by year (such as Category:Conflicts in 1878) corresponding to the date on which the battle was fought. Longer battles spanning several years may be placed in multiple year categories, or in the corresponding decade or century categories in extreme cases.
By period: battles can be placed in one of the sub-categories of Category:Battles by period to indicate which of the broad periods of military history they belong to. For example, battles involving the Roman Empire would be placed under Category:Battles of antiquity.
One frequently asked question about this category scheme is why battles are categorized by participants, rather than by location; why are there no "Battles in ..." categories, in other words? The answer is that, unlike categorizing by participants, which is relatively intuitive and extremely useful, categorizing by location produces a scheme that is unintuitive and difficult to work with, at best, and completely meaningless and impossible to maintain, at worst.
There are two basic options when categorizing battles by location: using the modern countries, or using the historical countries that existed at the time of the battle. The first option—using modern countries—results in a category scheme that makes meaningless connections based on changes in geography centuries after the events discussed in the articles in question. The Siege of Königsberg in 1262, for example, would be classified as a siege in Russia, despite Russia not being involved in any way at the time. Similarly, the campaigns of individuals such as Alexander the Great would be scattered among dozens of countries in a fairly arbitrary manner. This is, at best, a less intuitive approach than categorizing by participants.
Categorizing by the historical location is even more problematic. The chief difficulty is that, unlike the participants in a battle (which are almost always uncontroversial), the ownership of the land where a battle was fought is often a matter of significant historical controversy—having, at times, been the cause of the battle itself! In cases where the territory was historically a disputed one, arbitrarily assigning it to one of the countries involved is highly problematic, due to our policy on maintaining a neutral point of view. Even in cases where ownership can be determined, however, doing so is quite often neither obvious nor intuitive, and requires an unreasonably detailed knowledge of the various diplomatic events of the surrounding period; this is particularly problematic in medieval and early modern Europe, where cities and territories regularly changed hands. For example, the various sieges of Milan in the early 16th century took place—fairly unpredictably—within the territory of either the Duchy of Milan, France, or Spain, depending on which country had been the last to receive the city in one of the myriad treaties during the period. Unlike categorizing by historical participants, which can be done from almost any description of the battle itself, categorizing by historical location thus requires an exhaustive knowledge of obscure diplomatic concerns, and is at times simply impossible due to underlying territorial disputes.
By war: as an extension of the "by period" scheme, units associated with particular wars can be placed in one or more sub-categories of Category:Military units and formations by war; for example, units that fought in World War II are placed under Category:Military units and formations of World War II. This type of categorization is intended only for very major conflicts; creating a category tree for every recorded war is obviously unproductive.
By type: units with a special role (such as airborne, artillery, or armored units), structure (such as mercenary or irregular units), or composition (such as expatriate or all-female units) can be placed under the appropriate sub-category of Category:Military units and formations by type; for example, a cavalry unit would be placed under Category:Cavalry units and formations.
A particular article need not be categorized with all of the possible category types; for some topics, certain of the category options are inapplicable or inconvenient labels.
