In 1st Kings 15:1-8 we read a brief summation of the mark that Rehoboam's son Abijam (or Abijah) left on the pages of Judah's history. In this chapter one of the missing details is filled in. This is the story of his war with Jeroboam and Israel.
Now, Abijah was not a good man, nor was he a good king (1st Kings 15:3). He didn't even have an accurate view of his place or of his rights as king. However, he did have one basic thing going for him. He was convinced that Jehovah was real, good, able and willing to defend the name and heritage of David and Solomon. And, he was right.
Although Abijah was outnumbered 2 to 1, he was confident. Why? Because he believed that God was on his side. And, as I said, He was. Jeroboam's 800,000 were no match for Abijah's 400,000... because the captain of Judah was truly Jehovah Himself (2nd Chronicles 13:12). So, despite Jeroboam’s strategic advantage over Abijah (2nd Chronicles 13:13 & 14), the battle belonged to the Lord (Ecclesiastes 9:11). Judah won and ½ a million of Jeroboam's troops were killed (Psalm 124:1-8). Due to their faith in God, albeit momentary, the men of Judah... and their king, Abijah... were victorious. In the end, Jeroboam died (2nd Chronicles 13:20) and Abijah became a dominant force in the region (2nd Chronicles 13:21).