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The King’s Mirror as a Medieval Military Manual

by Brent E Hanner

The study of military manuals in the medieval period has been scanty at best.  The overpowering presence of Vegetius in the period has drawn scholars to study his writing’s role as a manual, largely ignoring other potential works from the period.  This is partially due to the large influence of Vegetius over general military thought in the early modern period.  But it also has allot to do with the fact that Vegetius was a very widely read and studied work during the middle ages.  Over 320 copies of Vegetius survive from the middle ages and many late medieval and early modern treatise were based on Vegetius such as Christine de Pizan’s The Book of Deeds of Arms and of Chivalry  and also Machiavelli’s influential treatise The Art of War.(1)

        While Vegetius is very important to study, in relation to the middle ages, we need not forget about other writers who wrote on military topics whose works are not wholly based on Vegetius and who often are working within other frame works.  Works such as The Rule of the Temple, which was the rules for the Knights Templar.  It shows an almost eerily modern military at work in the twelfth century, but has weaknesses in showing the Templars use of ground troops.  Many of the later treatise take the form of plans for taking the Holy Land.(2)   And who knows where all we will find treatise on the military in medieval works.

        One such place such works may be found are in encyclopedic works.  During the early and high middle ages writing works of encyclopedic knowledge was quite common.  This tradition extended from late-roman times until sometime in the thirteenth or fourteenth century.  These works cover everything from the seven liberal arts to how to be a king.  One such book has come down to us from thirteenth century Norway, called Speculum Regale or The King’s Mirror.  The King’s Mirror was written sometime around 1250 in Old Norse by an anonymous author.

         The King’s mirror is written as a conversation between a son and his father.  The author tells us that through this conversation he will tell us about the four areas of work in the world.  Those he says he will discuss include being a merchant, the royal court, clergy and lastly the life of peasants.  Only the first two have survived.  The last two either were not written or simple didn’t last through the last 600 years.  The second section is that part that we need to concern ourselves with.(3)   It contains what is basically a manual of how the king’s household should be run and what those who are in the king’s service should do.  Included are several sections discussing training, armaments, tactics for sea battles and a relatively large section on both offensive and defensive siege weapons.

         One aspect of medieval military thought that is totally lacking is any discussion from this work is the idea of “just war”.  From St. Augustine to Bonet the idea of a just war was defined and expanded.(4)   But even with the large section discussing kingship, which uses old testament biblical stories as references, there is no mention of the idea.  The closest statements to it refer to manslaying.  The father states:

You should abhor and avoid manslaying in every form except as a lawful punishment or in common warfare.  But in ordinary warfare on the lawful command of your chief, you need to shun manslaying no more than any other deed which you know to be right and good.(5)

This does not show anything within the realm of the just law ideas that had developed on the continent but it does give us an insight into the 13th century Norse view that killing in a war sanctioned by your rightful ruler is acceptable and even good.

         After the father discusses being a merchant he turns towards the royal household.  In the thirteenth century in almost every western nation, the line between royal household and the government of the country was just now beginning to separate.  During this century we see a great influx of documents that attempt to place the king under the law such as the Magna Carta.  No such system is described in the King’s Mirror.  In this system we see a very similar concept to the fyrd concept in AS England.  The idea that all men are required to serve when called upon by their king and that their ultimate loyalty lies in the king.(6)

        After describing the place of various levels of the king’s household the author goes onto describe the basic duties and ideals of the housecarl class.  The housecarl class is the basic equivalent to the knight in England and on the continent, as the mounted warrior class.  But the ideals while possessing some basic similarities have a few very distinct differences.  Just like the continental knightly class they were to “observe righteousness in every form”.(7)   This fits with the contemporary highly chivalric idea of the knightly class.  However, unlike the  continental knightly class the author says that, “They should be chosen from all classes and not from the wealthy or distinguished families only”.(8)   This is in sharp contrast to the idea of lineage of knighthood that was beginning to appear on the continent.

        After this discussion, the conversation turns towards dress and manners of address.  He then proceeds to tell us about times of dirth, which leads the boy to ask about the proper duties of a housecarl.  The father replies first with what a housecarl should not do including gambling, going to brothels, and drinking to excess.  He then proceeds onto the duties.  The first of which is the protection of the king and how to walk and travel as his escort.  After telling his son how to speak with the king and ignore the king’s business while he is discussing things, he describes how the guard should move with the king:

if you walk in equal numbers on either side of the king, though never in compact groups.  Wherever you go he should walk in your midst, and you and your companions should be arranged in equal numbers before and behind him and on either side.(9)

He also states that the same procedure should be used when riding, but more distance should be given.  The father then discusses various manners of address and eating.

         The father then begins to discuss the proper diversions for a housecarl in which he basically describes the ways in which a housecarl should train himself.  He starts off describing how one should ride when he goes out to ride for amusement.  He instructs his son to ride fully armored.  Then he instructs him to practice sitting in the saddle properly and the proper use of stirrups.  He then proceeds to discussing the proper placement of the shield and lance and how to grip both the shield and bridle with the left hand.  He then tells his son to learn to maneuver his horse at high speeds and to take good care of his horse.(10)

         The next training exercise the father describes as amusement is what basically equates to fencing.  He instructs his son to find a fellow housecarl and practice sword strokes.  He instructs his son that this should be done in heavy armor, such as mail or a heavy gambeson.(11)   This fits into our knowledge about the state of fencing around the year 1300.  The oldest known fencing manual, Tower I.33, is from Germany from around 1300 and the only major difference between what is being described and the fencing manual is that those shown in the manual are totally un-armoured.(12)   The Father then instructs his son that if he wishes to get good he needs to practice every day and if possible twice a day, except for holidays.

        Finally he ends the this discussion with a list of various other weapons that can be trained with if one gets bored with swords.   Included among these are the spear, the bow and the sling.  And interestingly enough he also points out that in the past warriors trained equally with both hand but that this is no longer done.  But he also instructs his son that if he finds himself gifted it is worth while.(13)

        Next the father discusses behavior in battle.  He tells his son not to shun killing in battle and to show courage and bravery.  One should fight in good spirit but with wrath and should be sure to throw good attacks and not waste them.  He also instructs his son never to be boastful about himself after a battle because there will always be those who have witnessed your deeds and it is their job to boast of you.

         In the final sections that discuss military ideas he discusses combat on foot, combat on ships, the armament of a horsemen and engines used in sieges.  These sections of the conversations have some interesting aspects to them.  In certain aspects the author almost seems to speak from personal experience where as in other parts he is very familiar with the material but not with their role in war.  There is some Vegetian influence in the sea combat and in the siege combat, but whether it is direct is hard to tell.  There is also a case to be made for a lack of familiarity with the use of horses in combat.

        He first begins speaking about fighting on foot in a land battle.  He discusses fighting in a wedge shaped column and how to dress the line.  He also tells his son to make sure the front edge of the shield is not behind his neighbors shields.  He instructs his son not to throw his spear unless he has another because a spear is the best weapon to fight on foot with. (14)  This appears to be the base tactic idea of the Vikings but it is mentioned by Vegetius but only in describing how to defeat such a formation.  Vegetius does not describe it nor give such details on the proper way to dress this kind of line.(15)

         Next he proceeds on to fighting on ships.  The father instructs his son to bring two spears, one for fighting across ships and the other one shorter for fighting once you get aboard.  He also instructs his son in the use of javelins and other darts aboard ships.  He also is sure to instruct his son to fight with an even temper.  The father then goes onto describe weapons that may be of use aboard ships.  In this listing he is probably influenced by Vegetius or by Vegetian ideas that had influenced warfare.  He mentions a “prow-boar” which is almost identical to what Vegetius refers to as a beam, which is basically a ram for use upon ships.  They also both describe fortifications on ships.  They also both describe what the proper equipment is to wear while fighting on ships.  In the King’s Mirror, he states almost as a afterthought that mail and large shields are useful but that a gambeson is better armor for fighting on ships.  Vegetius pushes for a heavily armed soldier as the proper marine.  But all of these things could simply show Vegetian influence in the time. (16)

         In the next section of the King’s Mirror the father describes in detail the armament of a housecarl, or knight.  This is an accurate description of a mid-thirteenth century knight from the continent.(17)   The father goes into such detail that he describes the knight from the underwear out.  There are some things of interesting note such as he says that a knight should carry two swords and a dagger along with his spear.  And that one of the swords should be hanging from his saddle.  He ends saying that mounted warriors may also use bows and week crossbows.  He makes no mention at all of the tactics of a mounted warrior.  We get a somewhat description of a charge and how it works from Maurice and in the Rules of the Order.(18)   But the author of Speculum Regale doesn’t mention it once.  It is almost as if he is instructing his audience on what they should be wearing to imitate the continental knight but he doesn’t actually know the proper tactics for the equipment.

         In the last and longest section on military thought in the King’s Mirror is that on sieges and their weapons of attack and defense.  He very systematically lists the weapons of attack and then weapons of defense and ideas on how to defend it.  Vegetius also does this in his De re Militari.  But unlike Vegetius in the King’s Mirror there is no mention of preparation or on how the proper way to build a fortification.  This shows the basic disregard for logistics that plagued the medieval army.  Vegetius mentioned thing in detail like which kinds of stones go where but the author of Speculum Regale mentions things that would have to have been prepared ahead of time but doesn’t tell you to prepare them just to use them.

        Once again we find some strong similarities between the King’s Mirror and Vegetius.  A few of particular note are when Vegetius describes, “Huge wheels are also made out of green wood, and cylindrical sections which they call taleae, are cut from very stout trees and smoothed to make them roll.” (19)  Whereas in the King’s Mirror the same basic thing is described, “A ‘running wheel’ is also a good weapon for those who defend castles:  it is made of two millstones with an axle of tough oak joining them.” (20)  This is practically the same engine being described although the later version is slightly modified.  We also see several other incidents of this such as with a description of the ram and the “falx” or “cat”, which is a sickle like device for tearing away walls.

         The King’s Mirror also shows several military developments in siege warfare since Vegetius.  The most distinctive is that of the trebuchet.  Instead of the torsion based mangonels, which according to Vegetius was to be used for defense, we find the counter-weight based trebuchet with is recommended for attacking the walls of a fortification.  We also find the interesting “shot wagon”, which is a wagon filled with stones that is rolled down a slope to the edge of the wall where it is stopped and the stones fly out.(21)

         The King’s Mirror is an interesting glimpse at the military thought of mid-thirteenth century Norway and it gives us and makes us question what other works of military thought could be hidden within larger works.  While the King’s Mirror shows the definite influence of Vegetius on the warfare of the ages it is not clear wether or not the author of a King’s Mirror had actually read or been exposed to Vegetius directly.  We don’t see any quoting or pattern matches between the two texts but there are definite similarities in content.  The King’s Mirror may also give us a glimpse of the military structure of 13th century Norway and even more could probably be learned about the military thought by examining the biblical stories contained at the end of the section on the king’s court.  They contain many references to warfare and a linguistic study of them may prove useful.


Bennet, Matthew. “La Regle du Temple as a Military Manual”, The Rule of the Templars (Woodbridge, Boydell Press, 1992).

Clark, Lt. John.  The Military Institutions of the Romans (Harrisburg, The Military Service Publishing Company, 1944).

Hooper, Nicholas and Matthew Bennet, Cambridge Illustrated Atlas: Warfare: The Middle Ages 768-1487 (Cambridge, Cambridge University Press, 1996).

Larson, Laurence Marcellus. The King’s Mirror (New York: Twayne Publishers, 1917).

Milner, N.P. Vegetius: Epitome of Military Science (Trowbridge, Liverpool University Press, 1993).

Niccole, David. Medieval Warfare Sourcebook: Warfare in Western Christendom (London, Brockhampton Press, 1999).

Niccole, David. Arms and Armour of the Crusading Era 1050-1350:Western Europe and the Crusader States (London, Greenhill Books, 1999).

Shrader, Charles R. “The Influence of Vegetius’ De re militari”  Military Affairs 45 no. 4 (1981).

End Notes

     1 Shrader, Charles R. “The Influence of Vegetius’ De re militari”  Military Affairs 45 no. 4 (1981): 168-170.
2 Nicholas Hooper and Matthew Bennet, Cambridge Illustrated Atlas: Warfare: The Middle Ages 768-1487 (Cambridge,    Cambridge University Press, 1996), 168.
3 Larson, Laurence Marcellus. The King’s Mirror (New York,Twayne Publishers, 1917),1-71
4 Niccole, David. Medieval Warfare Sourcebook: Warfare in Western Christendom (London, Brockhampton Press, 1999), 241-144
5 Larson, 214
6 Ibid., 175
7 Ibid., 177
8 Ibid.
9 Ibid., 208
10  Ibid., 211
11  Ibid., 212
12  the website on the Tower Fetchbuch has disapeared but I still have a copy of all the images from it.
13  Larson, 213
14  Ibid., 214
15  Clark, Lt. John.  The Military Institutions of the Romans (Harrisburg, The Military Service Publishing Company, 1944), 98
16  Larson, 215-217;  Milner, N.P. Vegetius: Epitome of Military Science (Trowbridge, Liverpool Universtiry Press, 1993), 149-151
17  Niccole, David. Arms and Armour of the Crusading Era 1050-1350:Western Europe and the Crusader States (London, Greenhill Books, 1999),  360
18  Bennet, Matthew. “La Regle du Temple as a Military Manual” in The Rule of the Templars (Woodbridge, Boydell Press,1992), 184-187
19  Milner, 125
20  Larson, 223
21  Ibid., 223

This article has been reprinted by permission of Brent E. Hanner.  It can also be found at www.swt.edu/~bh59648/75years/specregal.html

For a full translation of The King’s Mirror see www.swt.edu/~bh59648/75years/mirror/index.html

For the section specific to military affairs, see our section, at www.deremilitari.org/kingsmirror.htm

(via De Re Militari)