English: Uniform of Charles de Batz de Castelmore d'Artagnan, Captain-Lieutenant of the First Company of the Kings Musketeers When King Louis XIV became King of France, he instituted many changes to the look of his countries military. The Kings Musketeers, his personal guard, were of particular focus for King Louis XIV. He wanted to improve and update their dress in keeping with the fashion of the times. Officers in the Kings Musketeers wore frock coats to denote rank. Lieutenants wore a blue frock coat with scarlet cuffs and scarlet lining, a scarlet waistcoat with scarlet lining, and blue britches. Captains wore a blue frock coat with blue cuffs and scarlet lining, a blue waistcoat with scarlet lining and blue britches. Lieutenants and Captains frock coats and waistcoats were trimmed in silver. Another unique feature was the triple vented backs of these coats, typically was the style of gentry frocks alone in the 17th century. All though the Musketeer Cassock was the standard fare for the enlisted men, officers would wear them from time to time over their frocks. There are a few schools of thought as to why, but the one that makes the most sense is that in a battle, the officers would be harder to target among the ranks. This is the actual uniform worn by Musketeer Lieutenants and Captains during King Louis XIV's reign.