2 Samuel 10:16
And Hadarezer sent, and brought out the Syrians that were beyond the river: and they came to Helam; and Shobach the captain of the host of Hadarezer went before them. And Hadarezer sent, and brought out the Syrians that were beyond the river: and they came to Helam; and Shobach the captain of the host of Hadarezer went before them.
This gathering at Helam was part of a vast unprovoked coalition against David that sprang from jealousy of his increasing power and led to the greatest wars and victories of his reign and the most extensive additions to his power. The coalition formed after the Ammonites made themselves odious to David by scorning his ambassadors and hiring chariots and horsemen from Mesopotamia and Syria-maachah and Zobah. The inhabitants of the region between the Euphrates and the Mediterranean then joined the Ammonites, encircling the north and east of Canaan with armed foes banded to crush Israel.
The muster described here belongs to the second year of the Ammonite-Syrian war, when the allies renewed the war after being overcome in the first engagement fought under Joab. Hadarezer, the king of Syria, brought an immense Syrian army from beyond the river to Helam under Shobach, the captain of his host, threatening Israel. David, realizing how much depended on the result, took the field in person.
By the blessing of God David inflicted so disastrous a defeat that the Syrians from Lebanon to the Euphrates gave up the war and became tributary to Israel. David then pushed the war against the Ammonites until their strongholds fell and the whole region came under Israel's dominion.