Second Samuel 10 describes conflict beginning when Hanun king of Ammon humiliated messengers David had sent to express sympathy after the death of Hanun's father.
The Ammonites hired Aramean forces, but Joab and the Israelite army defeated the coalition. Hadadezer subsequently summoned additional Arameans from beyond the Euphrates under the command of Shobach.
These forces assembled at Helam. David personally led Israel across the Jordan and fought them there. Shobach was mortally wounded and the Arameans fled. The victory weakened Hadadezer and discouraged the Arameans from continuing to support Ammon against Israel.