Rukelion's plan was going more slowly than he would have liked. It took days for the clan leaders to come to a consensus but at least Kové's clan was onboard the whole time. He instructed his men accordingly and none of them were seriously hurt.
They identified each other based on tying certain colors around their sword grips. It was subtle enough that no one would notice it unless they were looking for it specifically.
That helped slow down the casualty rate and the other clan leaders noticed, which was what made them agree in the end. The problem after that was figuring out how to do this in the most natural-seeming way.
At least they had the advantage of Rukelion being a major. His instructions trumped those of captains so he was able to steer troops that weren't in on this elsewhere to help lessen the chance of people getting injured unnecessarily.