Their children, whom he raised up in their place, them did Joshua circumcise: for they were uncircumcised, because they had not circumcised them by the way.
Why did God wait to command the circumcision of the new generation until now rather than on the plains of Moab? Perhaps He did so because He wanted to bring the people into the land before enforcing this aspect of the Law. This is consistent with God’s dealings with humankind. He first gives and then asks (cf. Romans 12:1).