Halachaהלכה

Obligation to Fight in a Mandatory War

Jewish sources discuss who is obligated to participate in a milchemet mitzvah (a mandatory war), contrasting universal obligation in such wars with the exemptions that apply to optional warfare. The sources establish that in a mandatory war, virtually all categories of people—including grooms and brides—are obligated to serve.

אֲבָל בְּמִלְחֶמֶת מִצְוָה, הַכֹּל יוֹצְאִין

8 sources · all verified

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What the sources say

The foundational rule, established already in Mishnah Sotah 8:7 and confirmed by the Gemara in Sotah 44b, is that while the various exemptions from military service apply to an optional war, in a milchemet mitzvah everyone must go out — even a groom from his chamber and a bride from her pavilion.

the Rambam (Mishneh Torah, Melachim and Wars 5:1-2) defines milchemet mitzvah as comprising three categories: the war against the seven Canaanite nations, the war against Amalek, and coming to the aid of Israel against an enemy that attacks them — and for this last category, no court authorization is required; the king may compel the entire nation to go out on his own volition.

the Rambam (Mishneh Torah, Melachim and Wars 7:4-5) restates the universal obligation explicitly: in a milchemet mitzvah the entire nation must go out, and the Sefer HaChinukh (Sefer HaChinukh 526:3) confirms this ruling, noting that none of the individuals Scripture sends home from an optional war are dismissed when the war is a commanded one.

Source 1 · Tanach
Verified

Deuteronomy 20:5-8

דברים כ׳:ה׳-ח׳

Deuteronomy 20:5-8

These verses describe the exemptions for a new house, new vineyard, and betrothed woman before battle. Later sources use this section to contrast regular warfare with milchemet mitzvah, where exemptions are sharply curtailed.

וְדִבְּר֣וּ הַשֹּֽׁטְרִים֮ אֶל־הָעָ֣ם לֵאמֹר֒ מִֽי־הָאִ֞ישׁ אֲשֶׁ֨ר בָּנָ֤ה בַֽיִת־חָדָשׁ֙ וְלֹ֣א חֲנָכ֔וֹ יֵלֵ֖ךְ וְיָשֹׁ֣ב לְבֵית֑וֹ פֶּן־יָמוּת֙ בַּמִּלְחָמָ֔ה וְאִ֥ישׁ אַחֵ֖ר יַחְנְכֶֽנּוּ׃ וּמִֽי־הָאִ֞ישׁ אֲשֶׁר־נָטַ֥ע כֶּ֙רֶם֙ וְלֹ֣א חִלְּל֔וֹ יֵלֵ֖ךְ וְיָשֹׁ֣ב לְבֵית֑וֹ פֶּן־יָמוּת֙ בַּמִּלְחָמָ֔ה וְאִ֥ישׁ אַחֵ֖ר יְחַלְּלֶֽנּוּ׃ וּמִֽי־הָאִ֞ישׁ אֲשֶׁר־אֵרַ֤שׂ אִשָּׁה֙ וְלֹ֣א לְקָחָ֔הּ יֵלֵ֖ךְ וְיָשֹׁ֣ב לְבֵית֑וֹ פֶּן־יָמוּת֙ בַּמִּלְחָמָ֔ה וְאִ֥ישׁ אַחֵ֖ר יִקָּחֶֽנָּה׃ וְיָסְפ֣וּ הַשֹּׁטְרִים֮ לְדַבֵּ֣ר אֶל־הָעָם֒ וְאָמְר֗וּ מִי־הָאִ֤ישׁ הַיָּרֵא֙ וְרַ֣ךְ הַלֵּבָ֔ב יֵלֵ֖ךְ וְיָשֹׁ֣ב לְבֵית֑וֹ וְלֹ֥א יִמַּ֛ס אֶת־לְבַ֥ב אֶחָ֖יו כִּלְבָבֽוֹ׃

Then the officials shall address the troops, as follows: “Is there anyone who has built a new house but has not dedicated it? Let him go back to his home, lest he die in battle and another dedicate it. Is there anyone who has planted a vineyard but has never harvested it? Let him go back to his home, lest he die in battle and another harvest it. Is there anyone who has paid the bride-price for a wife, but who has not yet taken her [into his household]? Let him go back to his home, lest he die in battle and another take her to wife.” The officials shall go on addressing the troops and say, “Is there anyone afraid and disheartened? Let him go back to his home, lest the courage of his comrades flag like his.”

Source 2 · Tanach
Verified

Deuteronomy 20:1-9

דברים כ׳:א׳-ט׳

Deuteronomy 20:1-9

The Torah’s war legislation sets out the framework for war, including the public call to battle and the release of certain categories of soldiers in particular circumstances. It is the biblical basis for later discussions of war obligation and exemptions.

וְדִבְּר֣וּ הַשֹּֽׁטְרִים֮ אֶל־הָעָ֣ם לֵאמֹר֒ מִֽי־הָאִ֞ישׁ אֲשֶׁ֨ר בָּנָ֤ה בַֽיִת־חָדָשׁ֙ וְלֹ֣א חֲנָכ֔וֹ יֵלֵ֖ךְ וְיָשֹׁ֣ב לְבֵית֑וֹ פֶּן־יָמוּת֙ בַּמִּלְחָמָ֔ה וְאִ֥ישׁ אַחֵ֖ר יַחְנְכֶֽנּוּ׃ וּמִֽי־הָאִ֞ישׁ אֲשֶׁר־נָטַ֥ע כֶּ֙רֶם֙ וְלֹ֣א חִלְּל֔וֹ יֵלֵ֖ךְ וְיָשֹׁ֣ב לְבֵית֑וֹ פֶּן־יָמוּת֙ בַּמִּלְחָמָ֔ה וְאִ֥ישׁ אַחֵ֖ר יְחַלְּלֶֽנּוּ׃ וּמִֽי־הָאִ֞ישׁ אֲשֶׁר־אֵרַ֤שׂ אִשָּׁה֙ וְלֹ֣א לְקָחָ֔הּ יֵלֵ֖ךְ וְיָשֹׁ֣ב לְבֵית֑וֹ פֶּן־יָמוּת֙ בַּמִּלְחָמָ֔ה וְאִ֥ישׁ אַחֵ֖ר יִקָּחֶֽנָּה׃ וְיָסְפ֣וּ הַשֹּׁטְרִים֮ לְדַבֵּ֣ר אֶל־הָעָם֒ וְאָמְר֗וּ מִי־הָאִ֤ישׁ הַיָּרֵא֙ וְרַ֣ךְ הַלֵּבָ֔ב יֵלֵ֖ךְ וְיָשֹׁ֣ב לְבֵית֑וֹ וְלֹ֥א יִמַּ֛ס אֶת־לְבַ֥ב אֶחָ֖יו כִּלְבָבֽוֹ׃

Then the officials shall address the troops, as follows: “Is there anyone who has built a new house but has not dedicated it? Let him go back to his home, lest he die in battle and another dedicate it. Is there anyone who has planted a vineyard but has never harvested it? Let him go back to his home, lest he die in battle and another harvest it. Is there anyone who has paid the bride-price for a wife, but who has not yet taken her [into his household]? Let him go back to his home, lest he die in battle and another take her to wife.” The officials shall go on addressing the troops and say, “Is there anyone afraid and disheartened? Let him go back to his home, lest the courage of his comrades flag like his.”

Source 3 · Chazal
Verified

Mishnah Sotah 8:7

משנה סוטה ח׳:ז׳

Mishnah Sotah 8:7

The Mishnah distinguishes between milchemet mitzvah and milchemet reshut, stating that in a milchemet mitzvah everyone goes out. This is a foundational Chazal source for who is obligated in a mandatory war.

אֲבָל בְּמִלְחֶמֶת מִצְוָה, הַכֹּל יוֹצְאִין, אֲפִלּוּ חָתָן מֵחֶדְרוֹ וְכַלָּה מֵחֻפָּתָהּ.

Source 4 · Chazal
Verified

Sotah 44b

סוטה מ״ד ב

Sotah 44b

The Gemara elaborates on the Mishnah’s distinction between obligatory and optional war and explains that the exemptions listed elsewhere do not apply to a milchemet mitzvah. It is one of the core sugyot on universal obligation in mandatory war.

בַּמֶּה דְּבָרִים אֲמוּרִים — בְּמִלְחֲמוֹת הָרְשׁוּת, אֲבָל בְּמִלְחֲמוֹת מִצְוָה — הַכֹּל יוֹצְאִין, אֲפִילּוּ חָתָן מֵחֶדְרוֹ וְכַלָּה מֵחוּפָּתָהּ.

Source 5 · Rishonim
Verified

Mishneh Torah, Kings and Wars 5:1-2

משנה תורה, הלכות מלכים ומלחמות ה׳:א׳-ב׳

Mishneh Torah, Kings and Wars 5:1-2

The Rambam defines which wars are obligatory and states that in a milchemet mitzvah everyone goes out, even a groom from his chamber and a bride from her canopy. This is a central halakhic source for determining who is obligated to fight in a mandatory war.

אֵין הַמֶּלֶךְ נִלְחָם תְּחִלָּה אֶלָּא מִלְחֶמֶת מִצְוָה. וְאֵי זוֹ הִיא מִלְחֶמֶת מִצְוָה זוֹ מִלְחֶמֶת שִׁבְעָה עֲמָמִים. וּמִלְחֶמֶת עֲמָלֵק. וְעֶזְרַת יִשְׂרָאֵל מִיַּד צָר שֶׁבָּא עֲלֵיהֶם. וְאַחַר כָּךְ נִלְחָם בְּמִלְחֶמֶת הָרְשׁוּת וְהִיא הַמִּלְחָמָה שֶׁנִּלְחָם עִם שְׁאָר הָעַמִּים כְּדֵי לְהַרְחִיב גְּבוּל יִשְׂרָאֵל וּלְהַרְבּוֹת בִּגְדֻלָּתוֹ וְשִׁמְעוֹ: מִלְחֶמֶת מִצְוָה אֵינוֹ צָרִיךְ לִטּל בָּהּ רְשׁוּת בֵּית דִּין. אֶלָּא יוֹצֵא מֵעַצְמוֹ בְּכָל עֵת. וְכוֹפֶה הָעָם לָצֵאת. אֲבָל מִלְחֶמֶת הָרְשׁוּת אֵינוֹ מוֹצִיא הָעָם בָּהּ אֶלָּא עַל פִּי בֵּית דִּין שֶׁל שִׁבְעִים וְאֶחָד:

A king should not wage other wars before a milchemet mitzvah. What is considered as milchemet mitzvah? The war against the seven nations who occupied Eretz Yisrael, the war against Amalek, and a war fought to assist Israel from an enemy which attacks them. Afterwards, he may wage a milchemet hareshut, i.e. a war fought with other nations in order to expand the borders of Israel or magnify its greatness and reputation. There is no need to seek the permission of the court to wage a milchemet mitzvah. Rather, he may go out on his own volition and force the nation to go out with him. In contrast, he may not lead the nation out to wage a milchemat hareshut unless the court of seventy one judges approves.

Source 6 · Rishonim
Verified

Mishneh Torah, Kings and Wars 7:4-5

משנה תורה, הלכות מלכים ומלחמות ז׳:ד׳-ה׳

Mishneh Torah, Kings and Wars 7:4-5

Rambam discusses the exemptions and limits in war, including the distinction between optional and obligatory war. These halakhot help clarify the scope of personal obligation and when exemption rules do or do not apply.

וְאַחַר שֶׁחוֹזְרִין כָּל הַחוֹזְרִין מֵעוֹרְכֵי הַמִּלְחָמָה. מְתַקְּנִין אֶת הַמַּעֲרָכוֹת. וּפוֹקְדִים שָׂרֵי צְבָאוֹת בְּרֹאשׁ הָעָם. וּמַעֲמִידִין מֵאָחוֹר כָּל מַעֲרָכָה וּמַעֲרָכָה שׁוֹטְרִים חֲזָקִים וְעַזִּים. וְכַשִּׁילִין שֶׁל בַּרְזֶל בִּידֵיהֶם. הָרוֹצֶה לַחְזֹר מִן הַמִּלְחָמָה הָרְשׁוּת בְּיָדָן לַחְתֹּךְ אֶת שׁוֹקוֹ. שֶׁתְּחִלַּת נְפִילָה נִיסָה. בַּמֶּה דְּבָרִים אֲמוּרִים שֶׁמַּחְזִירִין אֲנָשִׁים אֵלּוּ מֵעוֹרְכֵי הַמִּלְחָמָה בְּמִלְחֶמֶת הָרְשׁוּת. אֲבָל בְּמִלְחֶמֶת מִצְוָה הַכּל יוֹצְאִין וַאֲפִלּוּ חָתָן מֵחַדְרוֹ וְכַלָּה מֵחֻפָּתָהּ:

After these individuals depart from the battlefront, the army is arrayed again and commanding officers are appointed at the head of the nation. Powerful officers with iron axes in their hands are placed in the rear of each array of troops. If a person wants to leave the battle, they have permission to chop off his legs, for flight is the beginning of defeat. In which instances are the above-mentioned individuals sent away from the battlefront? In a milchemet hareshut. By contrast, in a milchemet mitzvah, the entire nation must go out to war, even a groom from his chamber, and a bride from her pavilion.

Source 7 · Rishonim
Verified

Sefer HaChinukh 526

ספר החינוך תקכ״ו — ד"ה מִדִּינֵי הַמִּצְוָה

Sefer HaChinukh 526:3

The Chinukh explains the commandment framework for war and the obligation to fight when the community is commanded. It is useful for understanding how mitzvah-war obligation applies in a structured halakhic way.

מִדִּינֵי הַמִּצְוָה. מָה שֶׁאָמְרוּ זִכְרוֹנָם לִבְרָכָה (שם מד ב) שֶׁאֵין מַחְזִירִין מֵעוֹרְכֵי הַמִּלְחָמָה אֵלּוּ הַנִּזְכָּרִים בַּכָּתוּב אֶלָּא בְּמִלְחֶמֶת הָרְשׁוּת, אֲבָל בְּמִלְחֶמֶת מִצְוָה הַכֹּל יוֹצְאִין, אֲפִלּוּ חָתָן מֵחֶדְרוֹ וְכַלָּה מֵחֻפָּתָהּ. וּמָה שֶׁאָמְרוּ (מלכים ז, ד) שֶׁאַחַר שֶׁחָזְרוּ בְּמִלְחֶמֶת הָרְשׁוּת כָּל הַחוֹזְרִין, שֶׁהַנִּשְׁאָרִים מְתַקְּנִין אֶת הַמַּעֲרָכוֹת, וּפוֹקְדִין שָׂרֵי צְבָאוֹת בְּרֹאשׁ הָעָם, וּמַעֲמִידִין מֵאֲחוֹרֵי כָּל מַעֲרָכָה שׁוֹטְרִים חֲזָקִים וְכַשִּׁילִין שֶׁל בַּרְזֶל בִּידֵיהֶם, וְכָל הַמְּבַקֵּשׁ לַחְזֹר מִן הַמִּלְחָמָה הָרְשׁוּת בְּיָדָם לַחְתֹּךְ אֶת שׁוֹקָיו מִפְּנֵי שֶׁתְּחִלַּת נְפִילָה נִיסָה. וְיֶתֶר פְּרָטֶיהָ, מְבֹאָרִים בְּמַסֶּכֶת סוֹטָה [ה' מלכים ומלחמותיהם פ"ו ופ"ז].

From the laws of the commandment — that which they, may their memory be blessed, said (Sotah 44b) that we only send back from the battle lines those mentioned in Scripture in an optional war, but in a commanded war, everyone goes out [to war], even a groom from his room and a bride from her canopy; and that which they said (Mishneh Torah, Laws of Kings and Wars 7:4) that after all those sent back from an optional war are sent back, those left arrange the battle lines and appoint army leaders at the front of the people and position strong sentries at the back of all the battle lines [with] iron axes in their hands, and they have the authority in their hands to cut off the shins of anyone who seeks to leave from the war, since the beginning of [an army] falling is fleeing; and the rest of its details — are elucidated in Tractate Sotah. (See Mishneh Torah, Laws of Kings and Wars 6,7.)

Source 8 · Hasidic
Verified

Sefat Emet, Numbers, Beha'alotcha 15

שפת אמת, במדבר, בהעלותך ט״ו

Sefat Emet, Numbers, Beha'alotcha 15

One enters military service at age twenty, since at thirteen one becomes obligated in mitzvot and at twenty one becomes a "son of Torah" (as stated in the Zohar), and their wars were fought through the power of Torah—as Rashi explains in Parashat Devarim, they would not have needed weapons except for the sin of the spies, which is why the first generation is called "men of war.

ומבן עשרים יוצא למלחמה כי בן י"ג נעשה בר מצוה ובן כ' נעשה בן תורה כדאיתא בזוה"ק. וכל מלחמתן הי' בכח התורה כמ"ש רש"י בפ' דברים שלא היו צריכין כלי זיין לולי חטא המרגלים לכן דור ראשון נקראו אנשי המלחמה.