Don't worry about the ranks, I've got ways around that. It's that I have a concept of my officer, who is pretty much a sensitive, considerate but strong and calm who had seen through the war himself. Basically the ones who feels pain when seeing his men around him die, but is still following orders. His personality I think can work well in this scenario.

I could see more potential interactions if some characters are inexperienced draftees. But it's up to you to decide anyway. And I may have him present on the front line when combat happened. It'll be easier for interactions and I won't be sitting around in HQ when fights begin. I mean British majors do fight frequently according to what I know.

And discord, I would recommend. It is faster to talk stuff with each other. I mean a successful RP's OOC I am in right now is almost completely in discord, as talks are much quicker