Hi Bill
I haven't really researched the Dutch army, so I'll defer to the opinion of those more knowledgeable than I am on the subject of horse armour - or lack of it. From what I've read though, it doesn't look like Dutch troopers wore cuirasses or helmets during the Dutch war. Coat colour was most likely the ubiquitous grey/white with grey, red or blue linings, though a couple of units may have worn red coats. Lawson describes The Garde Te Paard (horse guards) as having blue coats faced blue, and the unit is likely to have worn that uniform throughout William's reign.
Eppinger's dragoons had hats as well as fur caps with cloth bags, so the second Dutch dragoon regiment in existence at the time may well have had both types of headgear as well (on the opposite side, French dragoons were definitely issued with a broad-brimmed felt hat for fatigue duties in addition to their cloth caps).
French troopers usually wore their buff coats under their cloth coats, meaning the former would have been visible only down the front. However, Eugène Leliepvre shows a French cavalryman wearing a sleeveless buff coat over his uniform coat (see pic below). Dunno how common this arrangement was as most period pictures show said buff coat worn either without a cloth coat or under it. Given that there was little standardisation at the time, Leliepvre's interpretation is not implausible, although he also shows the buff coat worn more conventionally under the coat.
Below is a 1678 engraving of a French trooper wearing a long-sleeved buff coat laced down the front and no cloth coat. A royal decree dated November 1671 ordered the line cavalry units to wear grey cloth coats while royal regiments (i.e regiments whose colonels were members of the royal family or princes of royal descent) were to wear blue, although it probably was a while before the new regulations were fully implemented.
And here's the Osprey booklet plate showing cavalrymen in both buff and cloth coats :
The only French cavalry regiment known to have worn armour were the
Cuirassiers du Roi. All other horse units seemed to have abandoned metal armour by the 1670's, despite some modern illustrations showing the occasional French trooper wearing a breastplate. Below are two pics of
Cuirassiers du Roi troopers during the 1670's :
One morning I shot an elephant in my pajamas. How he got into my pajamas I'll never know.
