Thanks for sharing these links. As fun as research can be, I have very little spare time due to my work commitments, so I rely on other people to do the hard work and post links and screenshots etc to the useful pictures and info on uniforms!
Interesting perspective on the "Marlborough at Ramillies" painting by Laguerre - I had always understood the dead figure without his wig at Marlborough's feet not to be a Frenchman but Marlborough's equerry Colonel Bingfield, who was famously decapitated by a cannonball while helping Marlborough remount during the battle. While the graphic decapitation could be shown on things like contemporary playing cards, an academic painting would not be so lurid and would simply show the unfortunate Bingfield in a pose of dignified death.
The reason for my interpretation is that there are two other dead figures in the foreground before Marlborough, and they very much resemble Allied horsemen (English and Dutch, or possibly Prussian) rather than Frenchmen who are shown in dark gray in the background melee.
Indeed Samogon, and I guess that only Monsieur Laguerre would be able to tell us what he intended by the prominent dead/prone figure in red. To my eyes the uniform of the casualty looks so much like that of a French Maison du Roi Gendarme ie: more so than a British officer, that I feel this is the intention of the artist; plus the fact that Marlborough himself seems remarkably composed in the painting, hardly the face of a man who has just in the last few minutes seen his aide decapitated...and indeed of a man who has missed being killed himself by a mere few centimetres.
But who are we to say after so many centuries have passed since the painting was made?