Charles Ellicott Commentary Judges 1:9

"And afterward the children of Judah went down to fight against the Canaanites that dwelt in the hill-country, and in the South, and in the lowland." — Judges 1:9 (ASV)

Went down to fight. — “Went up” is the phrase applied to military expeditions ; “went down” is the phrase for special battles (1 Samuel 26:10; 1 Samuel 29:4), like the Latin descendere in aciem. No doubt the phrase arose from the custom of always encamping on hills when it was possible to do so.

In the mountain, and in the south, and in the valley. — These are three marked regions of Palestine—the “hill-country” (ha-Har, Joshua 9:1), in which were Hebron and Debir (Judges 1:10–11); the south or Negeb (Joshua 15:21), in which were Arad and Zephath; and the valley, or rather lowlands (Shephelah, Joshua 11:16; Joshua 15:33), in which were the three Philistine towns of Gaza, Ashkelon, and Ekron (Judges 1:18). The Har is the central or highland district of Palestine, which runs through the whole length of the country, broken only by the plain of Jezreel.

The Negeb, derived from a root which means “dry,” was the region mainly occupied by the tribe of Simeon. The Shephelah, or low maritime plains (of which the root is perhaps also found in Hi-Spalis, Seville — see Stanley, Sinai and Palestine, 485), is Palestine proper, that is, the region of Philistia, the sea-coast south of the Plain of Sharon. In the English Version, the name is sometimes rendered as here, the valley (Deuteronomy 1:7; Joshua 9:1, and following), sometimes we find it as the plain (Obadiah 1:19, and following), or the low plains (1 Chronicles 27:28).