And when the Syrians saw that they were smitten before Israel,.... Considered it in their minds, and conversed with one another about it, and fearing what would be the consequence of it:
they gathered themselves together; not only the forces got together again, that fled before Joab, but all the kings of Syria united their forces together, as appears from 2-Samuel 10:19; supposing that David would avenge himself on them for assisting the Ammonites against him; and therefore judged it advisable to raise a large army, that they might be in a condition to receive him.

Here is a new attempt of the Syrians. Even the baffled cause will make head as long as there is any life in it; the enemies of the Son of David do so. But now the promise made to Abraham, Genesis 15:18, and repeated to Joshua, Joshua 1:4, that the borders of Israel should extend to the river Euphrates, was performed. Learn hence, that it is dangerous to help those who have God against them; for when they fall, their helpers will fall with them.

The Aramaeans, however, gathered together again after the first defeat, to continue the war; and Hadarezer, the most powerful of the Aramaean kings, sent messengers to Mesopotamia, and summoned it to war. It is very evident, not only from the words "he sent and brought out Aram, which was beyond the river," but also from the fact that Shobach, Hadarezer's general (Shophach according to the Chronicles), was at the head of the Mesopotamian troops, that the Mesopotamian troops who were summoned to help were under the supreme ruler of Hadarezer. This is placed beyond all possible doubt by 2-Samuel 10:19, where the kings who had fought with Hadarezer against the Israelites are called his "servants," or vassals. חילם ויּבאוּ (2-Samuel 10:16) might be translated "and their army came;" but when we compare with this the חלאמה ויּבא of 2-Samuel 10:17, we are compelled to render it as a proper name (as in the Septuagint, Chaldee, Syriac, and Arabic) - "and they (the men from beyond the Euphrates) came (marched) to Helam" - and to take חילם as a contracted form of חלאם. The situation of this place has not yet been discovered. Ewald supposes it to be connected with the Syrian town Alamatha upon the Euphrates (Ptol. Geogr. v. 15); but this is not to be thought of for a moment, if only because it cannot be supposed that the Aramaeans would fall back to the Euphrates, and wait for the Israelites to follow them thither before they gave them battle; and also on account of 2-Samuel 8:4 and 1-Chronicles 18:3, from which it is evident that Helam is to be sought for somewhere in the neighbourhood of Hamath. For חלאמה ויּבא we find אליהם ויּבא, "David came to them" (The Aramaeans), in the Chronicles: so that the author of the Chronicles has omitted the unknown place, unless indeed אליהם has been written by mistake for חלאם.