2 Chronicles 13

And when Judah looked around, to their surprise the battle line was at both front and rear; and they cried out to the Lord, and the priests sounded the trumpets. Then the men of Judah gave a shout; and as the men of Judah shouted, it happened that God struck Jeroboam and all Israel before Abijah and Judah. vv.14-15

Read chapter 13
A civil war is going on here in chapter thirteen.  Abijah is now king of Judah while Jeroboam is still king of Israel, put for the northern tribes.  Abijah appeals to Israel on the battlefield that they are not following God's ways and laws anymore, that the should quit while they're ahead so to say to become one nation again under Abijah's rule which is of the house of David.  Jeroboam and his men pay no attention and surround Abijah and his men from the front and the back- there's no way out.  But the men of Judah cry to the Lord in this surrounding that only God could get them out of- and He does!  God struck all the men of Israel right before their eyes.  Talk about an unlikely victory to the masses (kind of like Trump's victory of the presidency although I don't think he called on God).  Why did God choose to save Judah and not Israel?  The men of Judah were the one's that cried out to the Lord and added a shout of faith.  Abijah wasn't necessarily a god fearing man like his grandfather Solomon and great grand father David were, "it appears from the character of Abijah, 1 Kings 15:3, that he was not himself truly religious, yet he encouraged himself from the religion of his people. It is common for those that deny the power of godliness, to boast of the form of it."
When you're surrounded by your enemies may you cry out to God and shout to Him in victory!