in most cases, we were going with the idea that categories would be made down to the regimental size unit level. for peacetime it would be unit, country/branch, and for wartime it would be unit/country/branch, conflict. for instance
7th Cavalry Regiment, United States Army (a sub category of Cavalry Regiments, United States Army)
7th Cavalry Regiment, United States Army, American indian Wars (a sub category of American Indian Wars, United States Army)
7th Cavalry Regiment, United States Army, Korean War (a sub category of Korean War, United States Army)
when making the category, the "peacetime" entry will have pointers to the "wartime" entries noting to look there for the unit activities during that war, and the "wartime" categories would have a link back to the "peacetime" category noting to look there for activities other than that war.
beyond that, there are two many battalions, companies, troops, squadrons, platoons, squads, etc to make a lot of sense out of having them. if you have more detailed info on the unit, add the person to the regiment, then list in the profile the more detailed info, commander, dates served, etc.