Q. When I look at some of the pictures I see people in different color (Red, light blue, yellow as well as dark blue) hats. Is that a mistake?
A. The hat color (as well as rank insignia was color coded depending on job description. The colors was the same for both North and South. Artillery wore red, Cavalry wore yellow, infantry was light blue and general officers (and their staff) wore dark blue (union) or gray, (confederate). Sometimes it is hard to make a decision as to what the color should be. Generals and their staff always wore dark blue, but the others is a little bit of luck and detective work. For example, in the image of “Custer with Confederate prisoner” you can see that Lt. Washington is wearing a Yellow cap. On the ground behind him you see what appears to be a cap. Since we know that this was a classmate of Custer’s we did a little history game play. Perhaps the cap on the ground was Lt. Washington’s confederate cap and that Custer gave him his cavalry cap to wear for the picture. Obviously there is no way to know so each picture is a guess and some speculation as to what should be right.
Here are examples of all four (union) types of caps: