Medieval face-mask and transitional helmets.

Lost tomb, probably of Count William of Flanders,
Church of Saint Bertin, Saint Omer, Flanders, c.1170 or later

Nebuchadnezzar besieges Jerusalem, Rylands Beatus,
Commentary on the Apocalypse by Beatus of Liébana, c.1175, Spain
University of Manchester Library, Latin MS 8, f.206v

European with face-mask helmet
Carved Column Capital in the Cloister of Monreale Cathedral
near Palermo in Sicily, 1174 to 1182 AD

The Cardena Beatus Codex, c.1175-1185AD
Commentary on the Apocalypse by Beatus of Liébana, Spain
Folio 106r. The Antichrist Kills the Two Witnesses
Museo Arqueológico Nacional

The Hortus Deliciarum, Plate 3
Made at the Hohenburg Abbey, France, 1185AD
by Herrad of Landsberg

Wall Painting in the Church of Saints Giovanni & Paolo
Murder of Thomas Becket, Spoleto, Italy, late 12th-century

An inserted miniature in BL Harley 5102
Murder of Thomas Becket, England, late 12th-century

Rolandslied, Song of Roland,
Regensburg, Germany, late 12th-century
Universitätsbibliothek Heidelberg, Cod. Pal. germ. 112

Bible, Champagne, France, 1185-1195AD
Bibliothèque nationale de France, MS Latin 11534, f.157v.

The Martyrdom of Thomas Becket
Fresco in the Museo Diocesano
from Palazzo dei Trecento, Treviso, Veneto, Italy.
c.1180/90 or c.1360AD

The Murder of Thomas Becket, Archbishop of Canterbury
Font, Lyngsjo Church, Scania, southern Sweden, late 12th century

Soldiers in facemask helmets on the portal of Santa María la Real de Sangüesa, Navarre, c.1200.

Wall paintings of knights in All Saints Church, Claverley, Shropshire, c.1200.

and possibly

Effigy of Geoffrey de Mandeville, 1st Earl of Essex, 12th-13th century

Speculum virginum a.k.a. Jungfrauenspiegel, Trier, Germany, c.1180-1200.
Museum August Kestner, Hanover, inv 3984.

Sleeping Guards at the Sepulchre. Ávila Bible, Spain, 12th century.
Biblioteca Nacional VITR/15/1.

Relief of a Knight, Basilica di Santa Giustina, Padua, Italy, c.1190-1210AD.

Peace overcomes Discord,
Portal of Church of San Vincente Martyr at Frias, Burgos, Spanish late 12th century AD
(Cloisters Museum, New York).

Chartres Cathedral window
The story of the Murder of Thomas Becket, c.1210

Chartres Cathedral window w. 7 (Delaport 38), c.1213
The story of Charlemagne

Karlsschrein Shrine of Charlemagne, Aachen Cathedral, Germany, c.1215

Frescoes of 13th century North Italian Soldiers at Schloss Rodenegg (Rodeneck), 1215-1220.

Psalterium B. Elisabeth
Elisabethpsalter, Germany, early 13th century
Museo Archeologico Nazionale, Cividale Ms. CXXXVII

Bible, Paris, France, 1200-1225AD
Médiathèque de Troyes, MS 106, f.141v.

Speyerer Evangelista, c.1220AD
Badische Landesbibliothek, Karlsruhe, Ms Bruchsal 1, f.31v

Aeneasroman by Heinrich von Veldeke, c.1220
Staatsbibliothek zu Berlin, Ms. Germ. Fol. 282, Berlin

'Conquests of Alexander', Bible, France, c.1220AD.
Reims - BM - ms. 35, f.238v.

Fresco in the Church of Saint-Jacques-des-Guérets.
Departure of the knights for the second crusade, France, early 13th century

Iglesia de Nuestra Señora de la Asunción, en Sequera de Fresno.
Relief on a tympanum over a slit window.
Two soldiers in face-mask helmets, Spain, early 13th century.

St. Maurice on the Reliquary by Abbot Nantelme, 1225AD.
Monastery of Saint Maurice, Agaunum, Valais, Switzerland.

Soldiers & Hunters from The Rochester Bestiary, England, c.1230
British Library, Royal 12 F XIII

War Elephant from a Bestiary, England, 2nd quarter of the 13th century
British Library, Harley MS 4751.

Summa de vitiis et virtutibus by Willelmus Peraldus
British Library Harley MS 3244, England, after 1236.

Other 12th Century Illustrations of Costume and Soldiers
Other 13th Century Illustrations of Costume and Soldiers