Wars, causing death and destruction, are an ugly manifestation of human power. Yet for the Jews to function in this world they had to be prepared to fight against the evil in it, including through actual combat, even if a risk existed that they would overestimate the role of military might – a risk which the Torah points out.
What is being asked of us is demanding and complex. We must be consistently committed, though moments of clear Divine intervention are rare. Moments of inspiration have to be channeled into patterns of religious behavior. Being part of this world means we have to decide when to fight wars and when to make peace. After the era of prophets passed we have faith in Divine Providence but cannot be perfectly sure of how to interpret events. No longer slaves, the Jewish people face the burden and challenges of life in this world coupled with the opportunity to transform through the commandments given to us by Hashem.