The scattering of the concubine throughout Israel has the desired effect: outrage. Israel gathers up a huge army against their fellow tribe of Benjamites, demanding “hand over those scountrels in Gibeah, so that we may punish them to death, and purge the evil from Israel,” (Judges 20:13) to which the Benjamites more or less replied, nuts to you.
Now, this is not exactly a smart move. The Benjamites mustered about 26,000 troops while Israel recruited around 400,000 (Judges 20:15, 17). History is very fond of showing that the bigger army is more likely to win. Still, the Benjamites are not deterred. They won’t back down.
This really doesn’t make any sense. The men of Gibeah did a horrible thing, so why won’t the Benjamites turn them over? Try the criminals, convict them, and punish them. It should be that simple. Why did this get to the point of mustering armies to fight things out? This is not how civilized nations behave.
And, well, I guess they’re not. Israel is still very tribal. Despite the attempt to make a nation out of them by Moses and Joshua (yeah, I know, I need to get to them), they don’t appear to have any real maturity. If anything, the respective tribes are acting more like the individual brothers they take their heritage from. I have brothers, and I can tell you that stubborn obstinance is a default setting. When confronted by a brother about something, the instinct is to puff up the chest and say “Nuh uh!”
Heck, we only have to look back at how Joseph and his brothers interacted to see this in play. Joseph, the youngest, declares that he will rule over his brothers. What did they do? what any group of brothers would do: beat him up.
This story carries through that mentality on the tribal level. One entire tribe of brothers refuses to do what the others tell him to do, and there will be fighting. It’s guaranteed, because, like I said, they’re brothers.