John Calvin Commentary Joshua 11:21

"And Joshua came at that time, and cut off the Anakim from the hill-country, from Hebron, from Debir, from Anab, and from all the hill-country of Judah, and from all the hill-country of Israel: Joshua utterly destroyed them with their cities." — Joshua 11:21 (ASV)

And at that time came Joshua, etc. Of the sons of Anak we have spoken elsewhere. They were a race of giants, and the spies so terrified the people with the account of their mighty stature that they refused to proceed into the land of Canaan. Therefore, since they were objects of so much dread, it was important that they should be removed, and the people encouraged by their good hopes of success.

It would have been exceedingly injurious to keep such sources of alarm and anxiety constantly before their minds. This was because fear obscured the glory ascribed to God for former victories and overthrew their faith, as they reflected that the most difficult of all their contests still awaited them.

Therefore, not without cause is it mentioned among the other instances of divine aid that, by purging the land of such monsters, it was rendered a fit habitation for the people. The less believable it seemed that they could be successfully fought against, the more illustriously was the divine power displayed.