Judges 1:9
And afterward the children of Judah went down to fight against the Canaanites, that dwelt in the mountain, and in the south, and in the valley. And afterward the children of Judah went down to fight against the Canaanites, that dwelt in the mountain, and in the south, and in the valley.
Afterward the descendants of Judah went down to make war on the Canaanites who lived in the hill country and in the southern district and in the lowland valley, which proves that Judah did gain victories in the valleys and low country, as illustrated by Ekron as a city of the low country.
The verse stands within the introductory portion of the book formed by chapters 1 and 2 together with 3:1-6, which makes clear that the whole land had not yet been taken into possession.
It opens a new era in the history of Israel in which the people were left free to choose obedience and to build their national life aright, or to follow their own will and waste their freedom and their opportunities.
It belongs to the opening record of Israel's failure to fulfill the instructions given by God, of the captivity that followed as a consequence, and of the help provided through the judges, or deliverers, whom the Lord raised up for them.