When the Mishna teaches how the kohen mashu’ah milhamah – the priest who was anointed specifically for the purpose of leading the troops to war – concludes by telling the soldiers that anyone who was frightened of war was allowed to return home, we find two opinions about what that means. Rabbi Akiva says that it means simply what it says: someone who was frightened of the battlefield should not be placed in that situation. Rabbi Yossi haGalili argues that it refers to someone who is frightened because he knows that he has committed sins. He goes so far as to suggest that the reason the others (i.e. the people who variously planted vineyards, built houses or became engaged to women) were told to go home, was to offer an opportunity to the individual who had sinned to recuse himself without being embarrassed.
According to the Talmud Yerushalmi all of the people who are freed from army service needed to bring witnesses who would attest that they had, in fact, planted vineyards, built houses, etc. An opinion is brought in the Yerushalmi that this includes also the individual who sinned, who must bring witnesses that will testify before the shotrim or the mashu’ah milhamah as to his transgression. Since the testimony is not done in public, however, it is not viewed as a great embarrassment. According to this approach, even Rabbi Akiva would require some level of proof that the person was afraid, as the Mishna explains later, that the person loses control of his bodily functions – mayim shotetim al birkav (he urinates on his legs).
The expression of mayim shotetim al birkav refers to a situation where the psychological trauma of a given event causes a physiological reaction, like an uncontrollable shaking of the knees. Such a reaction, which involved involuntary tensing of muscles, also can cause a loss of control over bodily functions, leading to situations of incontinence.