The Syro-Ephraimite War takes place in the 8th century BCE, when Assyria is a great regional power.

The smaller nations of Syria (often called Aram) and the northern Kingdom of Israel (often called Ephraim because of the main tribe), had previously been tributary nations to Assyria.

Finally deciding to break away, they form a coalition in defense against the oncoming threat.

The southern Hebrew kingdom, known as Judah and ruled by King Ahaz, is loyal to Assyria and refuses to join the coalition.

In 735 BCE, Syria, under Rezin, and Israel, under Pekah, attempt yo depose Ahaz through an invasion.

Judah is being defeated and, according to 2 Chronicles, loses 120,000 troops in just one day.

Many significant officials are killed, including the king's son., and many others taken away as slaves.

(Telling of the same battle, 2 Kings 16:5 mentions no casualties and states that Rezin and Pekah failed to defeat Ahaz.

)During the invasion, the Philistines and Edomites take advantage of the situation to raid towns and villages within the southern kingdom.

Ahaz calls out to Tiglath-Pileser III of Assyria for help.

The Assyrians defend Judah, conquering both Israel and Syria, but the postwar alliance only brings more trouble for the king of Judah.

Ahaz has to pay tribute to Tiglath-Pileser III with treasures from the Temple in Jerusalem and the royal treasury.

He also installs idols of Assyrian gods in Judah to curry favor with his new ally.