Chamas: War, Hostages, and Silence in the Bible
Chamas, evil, is why the world is destroyed in the flood.
(יא) וַתִּשָּׁחֵ֥ת הָאָ֖רֶץ לִפְנֵ֣י הָֽאֱלֹהִ֑ים וַתִּמָּלֵ֥א הָאָ֖רֶץ חָמָֽס׃
(11) The earth became corrupt before God; the earth was filled with evil.
Sarah refers to Hagar's evil treatment of her as Chamas, but blames Abraham for her pain. Rashi explains the particular aspect of Chamas as an absence of "Protective words."
(ה) וַתֹּ֨אמֶר שָׂרַ֣י אֶל־אַבְרָם֮ חֲמָסִ֣י עָלֶיךָ֒ אָנֹכִ֗י נָתַ֤תִּי שִׁפְחָתִי֙ בְּחֵיקֶ֔ךָ וַתֵּ֙רֶא֙ כִּ֣י הָרָ֔תָה וָאֵקַ֖ל בְּעֵינֶ֑יהָ יִשְׁפֹּ֥ט יהוה בֵּינִ֥י וּבֵינֶֽיׄךָ׃
(5) And Sarai said to Abram, “The evil done me is on you! I myself put my maid in your bosom; now that she sees that she is pregnant, I am lowered in her esteem.
Judaism recognizes two categories of wars: Wars of Obligation/Mitzvah and Permitted/Self Defense Wars
(א)חמסי עליך. חָמָס הֶעָשׂוּי לִי, עָלֶיךָ אֲנִי מֵטִיל הָעֹנֶשׁ; כְּשֶׁהִתְפַּלַּלְתָּ לְהַקָּבָּ"ה מַה תִּתֶּן לִי וְאָנֹכִי הוֹלֵךְ עֲרִירִי, לֹא הִתְפַּלַּלְתָּ אֶלָּא עָלֶיךָ, וְהָיָה לְךָ לְהִתְפַּלֵּל עַל שְׁנֵינוּ, וְהָיִיתִי אֲנִי נִפְקֶדֶת עִמְּךָ, וְעוֹד דְּבָרֶיךָ אַתָּה חוֹמֵס מִמֶּנִי, שֶׁאַתָּה שׁוֹמֵעַ בִּזְיוֹנִי וְשׁוֹתֵק (בראשית רבה):
(1) THE EVIL IS ON YOU — The wrong done to me is on you because deprived me of your protecting words since you hear how I am despised and yet you keep silent (Genesis Rabbah 45:5).
Jerusalem Talmud, Sotah 8.10 -
Our Sages say: The wars of the House of David are an example of a permitted/optional war. The wars of Joshua are an example of an obligatory war.
Rabbi Judah called a permitted/optional war one in which we attacked them; an obligatory war one in which they attacked us.
רבנין אמרין מלחמת מצוה זו מלחמת דוד מלחמ' חובה זו מלחמת יהושע. רבי יהודה היה קורא מלחמת רשות כגון אנן דאזלין עליהון. מלחמת חובה כגון דאתיין אינון עלינן.
The lessons of King David: He is not punished for killing civilians in war, but he is not allowed to built the Temple because he has blood of innocent people on his hands.
אמר רבא מלחמות יהושע לכבש דברי הכל חובה מלחמות בית דוד לרווחה דברי הכל רשות כי פליגי למעוטי עובדי כוכבים דלא ליתי עלייהו מר קרי לה מצוה ומר קרי רשות נפקא מינה לעוסק במצוה שפטור מן המצוה
Rava said: With respect to the wars that Joshua waged to conquer Israel, all agree that they were obligatory. With respect to the wars waged by the House of King David for the sake of territorial expansion, all agree that they were elective wars. When they disagree, it is with regard to preventative wars that are waged to reduce the gentiles so that they will not come and wage war against them. One Sage, Rabbi Yehuda, called this type of war a mitzva, and one Sage, the Rabbis, called it an elective war. There is a practical difference between these opinions with respect to the principle: One who is engaged in a mitzva is exempt from performing another mitzva. According to Rabbi Yehuda, one fighting in this kind of war is exempt from performing another mitzva.
(ב) וַיָּ֨קָם דָּוִ֤יד הַמֶּ֙לֶךְ֙ עַל־רַגְלָ֔יו וַיֹּ֕אמֶר שְׁמָע֖וּנִי אַחַ֣י וְעַמִּ֑י אֲנִ֣י עִם־לְבָבִ֡י לִבְנוֹת֩ בֵּ֨ית מְנוּחָ֜ה לַאֲר֣וֹן בְּרִית־יהוה וְלַהֲדֹם֙ רַגְלֵ֣י אֱלֹהֵ֔ינוּ וַהֲכִינ֖וֹתִי לִבְנֽוֹת׃(ג) וְהָאֱלֹהִים֙ אָ֣מַר לִ֔י לֹא־תִבְנֶ֥ה בַ֖יִת לִשְׁמִ֑י כִּ֣י אִ֧ישׁ מִלְחָמ֛וֹת אַ֖תָּה וְדָמִ֥ים שָׁפָֽכְתָּ׃
(2) Then David the king stood up upon his feet, and said: ‘Hear me, my brethren, and my people; as for me, it was in my heart to build a house of rest for the ark of the covenant of the LORD, and for the footstool of our God; and I had made ready for the building.(3) But God said unto me: Thou shalt not build a house for My name, because thou art a man of war, and hast shed blood.

King David killed many innocent lives - and was not punished for it

(ח)דם לרוב שפכת. זה לא מצאנו שאמר לו השם אבל דוד אמר כן בלבו כי מפני זה מנעהו השם לבנות הבית... ובאמרו "דמים לרוב שפכת ארצה" כי דם נקיים היה בדמים אשר שפך כמו ... גם בדמי הגוים אשר שפך אותם שלא היו בני מלחמתו אפשר שהיו בהם אנשים טובים וחסידים אף על פי כן לא נענש עליהם כי כוונתו לכלות הרשעים שלא יפרצו בישראל, ולהציל עצמו כשהיה בארץ פלשתים לא יחיה איש ואשה, אבל כיון שנזדמן לו שפיכות דמים...:
You have shed much blood: ...because of this he [David] was prevented from building the Temple in Jerusalem. "You have shed much blood" refers so the innocent that were killed with the [wicked] others that he killed, for example... also non-Jewish blood that was shed of non-combatants, where there were possibly good and righteous people among them, nevertheless, David was not punished on account of this as his intention was to destroy the wicked so that the wicked did not spread in Israel, and in order to extricate himself from the Pelishtim he had to kill men and women...
Rodef: The Jewish Law of Self Defense
Permission to kill someone running after you with a knife before he kills you.
(ב)אין לו דמים. אֵין זוֹ רְצִיחָה, הֲרֵי הוּא כְמֵת מֵעִקָּרוֹ; כָּאן לִמְּדַתְךָ תוֹרָה "אִם בָּא לְהָרְגְּךָ, הַשְׁכֵּם לְהָרְגוֹ" וְזֶה לְהָרְגְּךָ בָּא, שֶׁהֲרֵי יוֹדֵעַ הוּא שֶׁאֵין אָדָם מַעֲמִיד עַצְמוֹ וְרוֹאֶה שֶׁנּוֹטְלִין מָמוֹנוֹ בְּפָנָיו וְשׁוֹתֵק, לְפִיכָךְ עַל מְנָת כֵּן בָּא שֶׁאִם יַעֲמֹד בַּעַל הַמָּמוֹן כְּנֶגְדוֹ יַהַרְגֶנּוּ (סנהדרין ע"ב):
(2) אין לו דמים THERE SHALL NO GUILT OF BLOOD BE INCURRED FOR HIM — This is not regarded as a murder; it is as though he (the thief) has been dead from the beginning of his criminal act (אין לו דמים is taken to mean: he, the thief, had no blood — no vitality). Here the Torah teaches you the rule: “If one comes with the intention of killing you, be quick and kill him”. — And this burglar actually came with the intention of killing you, for he knew full well that no one can hold himself in check, looking on whilst people are stealing his property before his eyes and doing nothing. He (the thief) therefore obviously came with this purpose in view — that in case the owner of the property would resist him, he would kill him (Sanhedrin 72a).
The Mitzvah of Redeeming Captives and its Limitations
פִּדְיוֹן שְׁבוּיִם מִצְוָה רַבָּה הִיא.
Redeeming captives is a great mitzva.
רָעָב קָשֶׁה מֵחֶרֶב – אִיבָּעֵית אֵימָא סְבָרָא: הַאי קָא מִצְטַעַר, וְהַאי לָא קָא מִצְטַעַר. אִיבָּעֵית אֵימָא קְרָא: ״טוֹבִים הָיוּ חַלְלֵי חֶרֶב מֵחַלְלֵי רָעָב״. שֶׁבִי [קָשֶׁה מִכּוּלָּם] – דְּכוּלְּהוּ אִיתַנְהוּ בֵּיהּ.
Famine is worse than the sword. If you wish, say that this is derived by way of logical reasoning: This one, who dies of famine, suffers greatly before departing from this world, but that one, who dies by the sword, does not suffer....And captivity is worse than all of them, as it includes all of them, i.e., famine, the sword, and possible death.
מַתְנִי׳ אֵין פּוֹדִין אֶת הַשְּׁבוּיִין יָתֵר עַל כְּדֵי דְּמֵיהֶן, מִפְּנֵי תִּיקּוּן הָעוֹלָם. וְאֵין מַבְרִיחִין אֶת הַשְּׁבוּיִין, מִפְּנֵי תִּיקּוּן הָעוֹלָם. רַבָּן שִׁמְעוֹן בֶּן גַּמְלִיאֵל אוֹמֵר: מִפְּנֵי תַּקָּנַת הַשְּׁבוּיִין.
MISHNA: Captives are not redeemed for more than their actual monetary value, for the betterment of the world; and one may not aid the captives in their attempt to escape from their captors for the betterment of the world, so that kidnappers will not be more restrictive with their captives to prevent them from escaping. Rabban Shimon ben Gamliel says: For the betterment of the captives, so that kidnappers will not avenge the escape of the captives by treating other captives with cruelty.
גְּמָ׳ אִיבַּעְיָא לְהוּ: הַאי ״מִפְּנֵי תִּיקּוּן הָעוֹלָם״ – מִשּׁוּם דּוּחְקָא דְצִבּוּרָא הוּא, אוֹ דִילְמָא מִשּׁוּם דְּלָא לִגְרְבוּ וְלַיְיתוֹ טְפֵי?
GEMARA:A dilemma was raised before the Sages: With regard to this expression: For the betterment of the world, is it due to the financial pressure of the community? Is the concern that the increase in price will lead to the community assuming financial pressures it will not be able to manage? Or perhaps it is because the result of this will be that they will not seize and bring additional captives, as they will see that it is not worthwhile for them to take Jews captive?
תָּא שְׁמַע: דְּלֵוִי בַּר דַּרְגָּא פַּרְקַהּ לִבְרַתֵּיהּ בִּתְלֵיסַר אַלְפֵי דִּינְרֵי זָהָב.אָמַר אַבָּיֵי: וּמַאן לֵימָא לַן דְּבִרְצוֹן חֲכָמִים עֲבַד? דִּילְמָא שֶׁלֹּא בִּרְצוֹן חֲכָמִים עֲבַד.
The Gemara suggests: Come and hear an answer based on the fact that Levi bar Darga redeemed his daughter who was taken captive with thirteen thousand gold dinars. This indicates that private citizens may pay excessive sums to redeem a captive if they so choose. Therefore, it must be that the reason for the ordinance was to avoid an excessive burden being placed upon the community. If the ordinance was instituted to remove the incentive for kidnappers to capture Jews, a private citizen would also not be permitted to pay an excessive sum.Abaye said: And who told us that he acted in accordance with the wishes of the Sages? Perhaps he acted against the wishes of the Sages, and this anecdote cannot serve as a proof.
Rabbi Joseph Karo in his 16th-century code of Jewish law, the Shulhan Arukh:
All who turn their gaze aside from the redemption of captives transgress the prohibitions:
‘thou shalt not harden thine heart, nor shut thine hand’
‘neither shalt thou stand against the blood of thy neighbour’
… and they disregard the commandments:
‘but thou shalt open thine hand wide unto him,’
‘that thy brother may live with thee,’
‘love thy neighbour as thyself,’
‘deliver them that are drawn unto death.’
And every minute that one delays in redeeming the captives, by every available means, it is as if one is spilling blood.