Joshua made himself flint knives, and circumcised the children of Israel at the hill of the foreskins.
The one redeeming fact about the awful punishment that befell Israel in the wilderness was that God, from the very first, promised to renew the nation to its former favored position when the years of the sentence against them were ended.  Here is the great importance of what happened in these verses.  Israel, by renewal of their faithful observance of such things as circumcision and the Passover, after having been assured of God's favor by their miraculous passage of the Jordan River, were now once again possessors of the Covenant.  The sentence of God against them was now fully executed by the passing of the 40 years, and their feet were firmly planted in Canaan!