There was no inner battle of conscience for Joshua to go and take the land out of the hands of its present inhabitants, since the Lord directly commanded him to do so. All the earth belongs to the Lord, and he alone has the right to dispose of it to whom he wills. God did so, in Joshua's case, through direct prophesy given to Israel, as well as accompanying them with supernatural power which granted them success. God continues to exalt nations today, as well as decimate them, in accordance with his “moral/revealed will” (Scripture), by the designs of Just War Theory (principles include: just cause, competent authority/legitimate government, right intention, humane methods, last resort/after diplomacy endeavors, and probability of success), as well as accompanying them with divine providence, in accordance with his “sovereign/hidden will” which grants them success.