This week's Mishpacha (translation: family) Magazine in English has a nice midrash on unity:
"Rabbi Yeshosuah of Schnin said in the name of Rabbi Levi, 'Schoolboys in the time of Dovid (king David), as long as they had not tasted sin, used to know how to derive 49 reasons from the Torah [to call an object spiritually] impure and 49 reasons [to call it spiritually] pure. And despite all that, [the Jews] would go out to war and fall in battle, because they spoke against each other.'
'But everyone in Achav's generation served idols, and nonetheless they would go out to war and be victorious, because they did not denounce one another.'"
What can be said? Oy.
BS"D - בסיעתא דשמיא