"and not melt the heart of his brothers as his own heart." R. Shimon says: If one hears the words of the Cohein and (they apply to him) and he does not return, in the end, all will return because of him.
(Devarim 20:9) "And it shall be, when the officers finish speaking to the people, they shall appoint commanders at the head of the people," and at the rear of the people. Sentinels armed with iron staves are posted before and behind them with the authority to "cripple" all who desire to flee, for the beginning of defeat is flight, as it is written (I Samuel 4:17) "Israel fled before the Philistines, and a great 'plague' overtook the people." When is this so? (that all of the aforementioned return?) In an optional war; but in a mandatory war, all go out, even a groom from his chamber and a bride from her bridal canopy.