Sotah8: 6
”וְהָיָה כְּכַלֹּת הַשֹּׁטְרִים לְדַבֵּר אֶל הָעָם וּפָקְדוּ שָׂרֵי צְבָאוֹת בְּרֹאשׁ הָעָם”, וּבַעֲקֵבוֹ שֶׁל עָם. מַעֲמִידִין זְקִיפִין לִפְנֵיהֶם, וַאֲחֵרִים מֵאֲחוֹרֵיהֶם, וְכַשִּׁילִין שֶׁל בַּרְזֶל בִּידֵיהֶן, וְכָל הַמְבַקֵּשׁ לַחֲזוֹר, הָרְשׁוּת בְּיָדוֹ לְקַפַּח אֶת שׁוֹקָיו, שֶׁתְּחִלַּת נִיסָה נְפִילָה, שֶׁנֶּאֱמַר: ”נָס יִשְׂרָאֵל לִפְנֵי פְלִשְׁתִּים וְגַם מַגֵּפָה גְדֹלָה הָיְתָה בָעָם”, וּלְהַלָּן הוּא אוֹמֵר: ”וַיָּנֻסוּ אַנְשֵׁי יִשְׂרָאֵל מִפְּנֵי פְלִשְׁתִּים וַיִּפְּלוּ חֲלָלִים וְגוֹ› ”.
And it shall be, when the officers have finished addressing the people, that they shall appoint captains of the host at the head of the people (Deut. 20:9) —- and at the rear of the people. They stationed guards in front of them, and others behind them with axes of iron in their hands; and if anyone tries to turn back, he has the authority to break his legs —- for flight is the beginning of slaughter, as it is said (I Samuel 4:17): Israel has fled from before the Philistines and there has been also a great slaughter among the people. And below it states (I Samuel 31:1): And Israel fled before the Philistines and they fell slain, etc.