How can we associate specific colors with specific categories?
For example, a report containing "Military Service" as a dimension should always have blue associated with Navy, green for Army, etc.
It appears that Cognos associates bar colors with an index into a color palette. So that if you made blue the first color in the palette, then the chart displays blue bars for whatever the first category value is - if Navy was first, you'd get the blue you want, but if Army was first, then it would make Army blue.
Any ideas?
Take a look at the conditional palette. If you have an exhaustive set of categories you can create a string variable and assign a colour using the conditional palette in the combination chart properties. Hope this helps.