 The poor knights originally wore red mantles , each of which bore St George 's Cross , but did not depict the Garter . Queen Elizabeth I replaced the mantles in the 16th and 17th centuries with blue and purple gowns , but the red mantles returned in the 17th century under King Charles I. When the knights were renamed , the mantles were abandoned . The military knights now wear the old military uniform of an " army officer on the unattached list " : black trousers with red stripe , a red double @-@ breasted swallow @-@ tailed coat , gold epaulets and brushes , a cocked hat with a plume , and a sword on a white sash . 
