Because some men in the Benjamite
town of Gibeah wanted to have same-sex sex with a Levite and his male servant who were staying the night in the town, it ended up with the tribe of Benjamin nearly wiped out by their own brothers, with the exception of "600 men who fled into the desert to the rock of Rimmon.
Did the Benjamites bind the right arms of their sons to their sides to encourage use of the left hand?
Some modern authors suggest that Benjamites and others may have encouraged left-handedness because it would be advantageous in combat.
There is a striking difference between these two episodes: the Israelites tolerated the idol of Micah, yet they went to war to punish the Benjamites for raping and murdering the concubine of Gibeah.
And it was on this account [Rashi: Micah's idol, which Israel didn't object to] that the people involved in the affair of the concubine at Gibeah were punished [Rashi: That the Benjamites killed 40,000].