Ellicott's Commentary On The Whole Bible
1 Chronicles 19:17
Came upon them. — Samuel, “came to Hêlâm.” The chronicler seems to have substituted an intelligible phrase for the name of an unknown locality. Professor Sayce has suggested to the writer that this mysterious Helam is no other than Aleppo, the Halman of the Assyrian monuments.
Upon them... against them. — Literally, unto them (’alêhem). The Hebrew term, “to Helam” (Helâmah), contains the same consonants as this prepositional phrase, with one extra. Perhaps, however, the term Helâmah was understood as a common noun implying to their army (hayil, hêl, army).
So when David had put the battle in array against the Syrians. — Literally, And David set the battle, &c., a needless repetition of the last clause. Probably Samuel is right: “And Aram put the battle in array against David.”