Divrey Hayamim Bais 22:1

1 2 And the inhabitants of Yerushalayim made Achazyahu (Ahaziah of Judah) his (i.e., Yehoram’s) youngest son melech in his place; for the troops that came with the Arabs into the machaneh had slain all the eldest. So Achazyahu (Ahaziah) ben Yehoram Melech Yehudah reigned.

Divrey Hayamim Bais 22:1 Meaning and Commentary

2 Chronicles 22:1

And the inhabitants of Jerusalem made Ahaziah his youngest
son king in his stead
He being the only surviving one of the sons of Jehoram, the same with Jehoahaz, ( 2 Chronicles 21:17 ) who was saved when the rest were taken captive and slain, by his mother Athaliah, and he made his escape, and that she also escaped is clear from ( 2 Chronicles 22:10 )

for the band of men that came with the Arabians to the camp;
that is, of the Philistines, ( 2 Chronicles 21:16 ) , which band seems to be a band or company of thieves and robbers, as the Septuagint, cruel and barbarous, as the action ascribed to them shows:

[for they] had slain all the eldest;
sons of Jehoram; the Philistines and Arabians only carried them away captives, but those slew them in cold blood:

so Ahaziah the son of Jehoram king of Judah reigned;
being declared his successor by the inhabitants of Jerusalem.

Divrey Hayamim Bais 22:1 In-Context

1 2 And the inhabitants of Yerushalayim made Achazyahu (Ahaziah of Judah) his (i.e., Yehoram’s) youngest son melech in his place; for the troops that came with the Arabs into the machaneh had slain all the eldest. So Achazyahu (Ahaziah) ben Yehoram Melech Yehudah reigned.

2 Twenty and two years old was Achazyahu (Ahaziah) when he began to reign, and he reigned one year in Yerushalayim And shem immo was Atalyah bat Omri (i.e., granddaughter of Omri the father of Ahab).

3 He also walked in the darkhei Bais Ach’av (Ahab); for immo (his mother) was his counselor to do rah.

4 Therefore he did rah in the eyes of Hashem like the Bais Ach’av (House of Ahab); for they were his yo’atzim (counselors) after the mot (death) of his av to his (i.e., Achazyahu’s, Ahaziah’s) ruin.

5 He walked also after their etza (advice, counsel), and went with Yehoram ben Ach’av Melech Yisroel to war against Chatzael Melech Aram (Syria) at Ramot Gil’ad; and the Syrians wounded Yoram.