וַתַּעֲרֹ֤ךְ יִשְׂרָאֵל֙ וּפְלִשְׁתִּ֔ים מַעֲרָכָ֖ה לִקְרַ֥את מַעֲרָכָֽה׃
И Израиль, и Филистимляне положили начало битве, армия против армии.
Rashi on I Samuel
Yisroel deployed. Referring to Yisroel's battalions.13That is why the feminine form [וַתַּעֲרֹךְ] is used because it is referring to מַעֲרָכָה which is grammatically feminine.