You may well be correct.

I had asked an artist friend to look at it and was told there were "stylistic" differences in the presentation of the "red" wagons from the "blue-grey" and "brown" wagons. Further, some of the red wagons appear to have been painted before the red was applied.

The style variation could have arisen from the paint (in the picture of the painting it does not appear to have the same "qualities" as the paint used for other colors) or the artist (poor mixing or incorrect use of the red paint - note how the "same" red is used above the fire - in contrast to the red on the lance pennant).

The "wash" aspect came out of this discussion of the paint's qualities (my friend asked if someone had "done" something to the painting - thus the "restorer" - though the cracks in the red of a few wagons, suggest to me there has not been a restoration with respect to the red wagons).

The possibility of artist error caused me to include the phrase "artist's intent".

The "same" large wagons - one red and one blue-grey - just below the cavalry also lead to questions (one could even compare the smaller red wagon and believe it was supposed to be a caisson; note how the "sets" above the cavalry have blue-grey caisson in front of a red wagon).

From our side, it was fun to speculate.

For your side, again, you may well be 100% correct. - R