From Barber (1978) pg 87-89.
Alfonso XI of Castile founded an Order in 1332 whose member wore white surcoats with a vermilion sash
As broad as a man’s hand worn over cloaks from the left shoulder to the waist [? diagonally]:
and they were called the knights of the Sash (de la Banda) and had statutes among themselves on
many good matters, all of which were knightly deeds. And when a knight was given the sash, he
was made to swear and promise to keep all the things that were written in that book of statues.
And the king did this so that men wishing to have that sash would have reason to do knightly
deeds. And it happened afterwards that if a knight or squire did such a feat of arms against the
king’s enemies, or tried to perform such a feat, the king gave him a sash and did him high
honour, so that all the others wished to do good knightly deeds to gain that honour and the
goodwill of the king, like those who already had it.
Alfonso seems to have tried to
Create a corps of gentlemen who would distinguish themselves by knightly deeds and who would
prepare for war by constant physical exercise: and to group round himself and his successors an
elite body whose members, bound by a special oath of loyalty and entirely devoted to the
sovereign’s person, would be a solid support for royal authority at a time when it was weak and
ill-established.
They served in the same squadron in the royal army on campaign.
References
Barber, R. (1978). Edward, Prince of Wales and Aquitaine: A biography of the Black Prince. Allen Lane, London.