Only scattered documentary and archaeological evidence is available for the Migration period and early Middle Ages, which makes any detailed analysis practically impossible. Sometimes precisely this scarcity of sources can give a misleading impression as to an allegedly particular fashion, as for instance in the case of the famous Bayeux Tapestry. Giving a pictorial account of the Norman conquest of Anglo-Saxon England culminating in the Battle of Hastings in 1066, the tapestry shows the majority of Norman men-at-arms as wearing a particular type of conical helmet with a face-protection in the shape of a nasal bar. It is the fame of this evidence, provided by the survival of a singularly outstanding work of art, that has largely contributed to such helmets being referred to as “Norman helmets.” However, this type of helmet had already been worn by Viking warriors of earlier periods (before their settlement in Normandy during the tenth century), and a closer look at the tapestry reveals that some of the Anglo-Saxon men-at-arms wear the same helmets as their Norman adversaries. Moreover, during the eleventh, twelfth, and thirteenth centuries, nasal helmets are in fact frequently found in depictions of men-at-arms from most other regions of medieval Europe.
When evidence becomes more readily available in larger quantities for the eleventh to the early thirteenth centuries, however, it can be established that, very generally speaking, the appearance of men-at-arms throughout Europe varied only to a small extent during this period. Indeed, the equipment and appearance of twelfth- and early thirteenth-century knights and men-at-arms from England would have differed little from those of their French, German, or Italian counterparts. Usually, such armor would comprise a mail shirt with attached hood and gauntlets, as well as mail leggings (chausses). On top of these a long flowing tunic (surcoat) could be worn, which was often girded with a belt, while a helmet (usually a so-called pot helm or barbiere, or a war hat) provided additional protection for the head. In all but the helmet, this appearance closely mirrored the civilian costume worn throughout Europe at the time. It is during the later part of the thirteenth century that regional differences in armor, especially the defenses for the arms and legs, begin to appear in France, England, Italy, and the Holy Roman Empire.
One of the first markedly noticeable instances of fashion in armor appears to be the use of small shoulder shields (ailettes), which were directly attached to the shoulders or upper arms as protection and/or a heraldic device. These ailettes were in vogue from about 1250 to the mid-fourteenth century, but were worn almost exclusively in France, or regions under strong French influence such as England and Flanders. Most of the scattered examples for the rare use of ailettes in Italy, the German-speaking lands, and Scandinavia appear to be also due to some form of French influence.
Breiding, Dirk H. “Fashion in European Armor, 1000–1300.” In Heilbrunn Timeline of Art History. New York: The Metropolitan Museum of Art, 2000–. http://www.metmuseum.org/toah/hd/afas13/hd_afas13.htm (October 2004)