douchiuchi (窶慊ｯﾅｽm窶慊｢窶堋ｿ)

This intruiged me when I found it in my dictionary.
It means : to kill eachother by mistake.
窶慊ｯﾅｽm = doushi : companion
窶慊｢窶堋ｿ = utsu : to attack

I guess it is used for Samurai who were fighting and in the heat of battel they accidentaly killed eachother :?. It's strange that they have a word for it, can any one give me an explanation for this ? Or Similar words

Well in the military the term is Friendly Fire. I am assuming the term is ment for when there are large groups fighting and you might not know all of your allies. That is why many groups that fought in large engagements would use colord armbands, or other markings to identify friendly units to each other.