Alfonso VIII of Castile and Eleanor of Plantagenet delivering the Castle of Uclés to the Master of the Order of Santiago, Pedro Fernández

Alfonso VIII of Castile and Eleanor of Plantagenet delivering the Castle of Uclés to the Master ("magister") of the Order of Santiago, Pedro Fernández. This is a miniature of the Tumbo Menor de Castilla, found in the Archivo Histórico Nacional in Madrid.
13th century

The knight of Santiago is referenced as figure 70 BRETHREN OF THE SPANISH MILITARY ORDERS in Armies of Feudal Europe 1066-1300 by Ian Heath
Figure 70, from a ms. of the reign of Alfonso VIII (1158-1214), depicts the habit of a brother knight of the Order of Santiago, apparently made of some kind of very coarse material.

Other Spanish Illustrations of Costume & Soldiers.
13th Century Illustrations of Costume & Soldiers.