Jamieson, Fausset and Brown on Judges 1:8

8. Now the children of Judah had fought against Jerusalem, and had taken it--The capture of this important city, which ranks among the early incidents in the war of invasion (Jos 15:63), is here noticed to account for its being in the possession of the Judahites; and they brought Adoni-bezek thither [Jud 1:7], in order, probably, that his fate being rendered so public, might inspire terror far and wide. Similar inroads were made into the other unconquered parts of Judah's inheritance [Jud 1:9-11]. The story of Caleb's acquisition of Hebron is here repeated (Jos 15:16-19). [See on Jos 15:16.]