There is too big of a learning curve for some anons.
#1 Israel and Judah were two separate nations at the time of this war.
#2 Israel totally kicked Moab's hind end
#3 Moab's king did a horrific and blasphemous thing (offering his son as a sacrifice,)
#4 His allies forsook him (and the 700 soldiers he had left.)
#5 Judah was one of his allies, and they were horrified at the King of
Moab's barbaric act, forsook him, and fled (because they weren't about to be allied with anyone who did such despicable things.)
#6 Even Edom (descendant's of Jacob's brother Esau) though pagans themselves, were sickened by the sacrifice of the king's son, and took off.
^^^^^^^^^^^
This guy must have just read a Bible for the first time today…
Congratulations!
Read Moar, Lurk Moar.