When the Israelites went to war, it was a Levite priest that addressed the troops before battle to remind them that it was The Lord who was fighting for them, "for The Lord your God is He that goes with you" (see also "Strong Is He Who Has Come Down").
"When you go forth to war against your enemies, and see horses and chariots and an army larger than your own, you shall not be afraid of them; for The Lord your God is with you, who brought you up out of the land of Egypt. And when you draw near to the battle, the priest [see Levites; also The Lines Of Eleazar and Ithamar] shall come forward and speak to the people, and shall say to them, 'Hear, O Israel, you draw near this day to battle against your enemies: let not your heart faint; do not fear, or tremble, or be in dread of them; for The Lord your God is he that goes with you, to fight for you against your enemies, to give you the victory.'" (Deuteronomy 20:1-4 RSV)
Then the battle commanders addressed the volunteer army with one last chance to withdraw themselves for just cause.
"Then the officers shall speak to the people, saying, 'What man is there that has built a new house and has not dedicated it? Let him go back to his house, lest he die in the battle and another man dedicate it. And what man is there that has planted a vineyard and has not enjoyed its fruit? Let him go back to his house, lest he die in the battle and another man enjoy its fruit. And what man is there that has betrothed a wife and has not taken her? Let him go back to his house, lest he die in the battle and another man take her.'" (Deuteronomy 20:5-7 RSV)
The rules of engagement for the Israelites differed according to where the battle took place. If it was outside the promised land, the enemy was allowed a chance to surrender; if they didn't, all males were to be killed, while everyone and everything else could be taken as booty. On the other hand, if it were within the promised land, the enemy troops and population were to be annihilated - without destroying the trees, which would be the Israelites' because they were within the prescribed borders of the land of Israel.
"When you draw near to a city to fight against it, offer terms of peace to it. And if its answer to you is peace and it opens to you, then all the people who are found in it shall do forced labor for you and shall serve you. But if it makes no peace with you, but makes war against you, then you shall besiege it; and when The Lord your God gives it into your hand you shall put all its males to the sword, but the women and the little ones, the cattle, and everything else in the city, all its spoil, you shall take as booty for yourselves; and you shall enjoy the spoil of your enemies, which The Lord your God has given you. Thus you shall do to all the cities which are very far from you, which are not cities of the nations here.
Deuteronomy Chapter 21
As stated above, foreign women from cities outside of the promised land of Israel could be taken alive. They could be married if they chose to be; if the woman refused the marriage, she was free to leave.
"When you go forth to war against your enemies, and The Lord your God gives them into your hands, and you take them captive, and see among the captives a beautiful woman, and you have desire for her and would take her for yourself as wife, then you shall bring her home to your house, and she shall shave her head and pare her nails. And she shall put off her captive's garb, and shall remain in your house and bewail her father and her mother a full month; after that you may go in to her, and be her husband, and she shall be your wife. Then, if you have no delight in her, you shall let her go where she will; but you shall not sell her for money, you shall not treat her as a slave, since you have humiliated her." (Deuteronomy 21:10-14 RSV)
The rights, and responsibilities, of the firstborn son was a direct foreshadow of the Christ (see Christ's Pentecost)
"If a man has two wives, the one loved and the other disliked, and they have borne him children, both the loved and the disliked, and if the first-born son is hers that is disliked, then on the day when he assigns his possessions as an inheritance to his sons, he may not treat the son of the loved as the first-born in preference to the son of the disliked, who is the first-born, but he shall acknowledge the first-born, the son of the disliked, by giving him a double portion of all that he has, for he is the first issue of his strength; the right of the first-born is his." (Deuteronomy 21:15-17 RSV)
"And if a man has committed a crime punishable by death and he is put to death, and you hang him on a tree, his body shall not remain all night upon the tree, but you shall bury him the same day, for a hanged man is accursed by God" (Deuteronomy 21:22-23 RSV)
Deuteronomy Chapter 22
God is pure; His creation was to be a reflection of the ultimate Creation that is yet to come (see The City To Come). In the mean time, simple things of life were to be "pure."
"A woman shall not wear anything that pertains to a man, nor shall a man put on a woman's garment [see Clothing In Bible Times]; for whoever does these things is an abomination to The Lord your God." (Deuteronomy 22:5 RSV)
Physical adultery was a capital offense because physical marriage itself was symbolic of a greater marriage to come (see "Thou shalt not commit adultery").
"If a man is found lying with the wife of another man, both of them shall die, the man who lay with the woman, and the woman; so you shall purge the evil from Israel." (Deuteronomy 22:22 RSV)
Deuteronomy Chapter 23
The rules of purity naturally applied to prevention of disease epidemics within a highly-populated camp.
"When you go forth against your enemies and are in camp, then you shall keep yourself from every evil thing. "If there is among you any man who is not clean by reason of what chances to him by night, then he shall go outside the camp, he shall not come within the camp; but when evening comes on, he shall bathe himself in water, and when the sun is down, he may come within the camp. You shall have a place outside the camp and you shall go out to it; and you shall have a stick with your weapons; and when you sit down outside, you shall dig a hole with it, and turn back and cover up your excrement. Because The Lord your God walks in the midst of your camp, to save you and to give up your enemies before you, therefore your camp must be holy, that he may not see anything indecent among you, and turn away from you." (Deuteronomy 23:9-14 RSV)
God's Law required both business responsibility and compassion. Poor people or hungry travelers (Christ Himself was an example of "When you go into your neighbor's standing grain" rule as quoted below i.e. "At that time Jesus went through the grainfields on the Sabbath; His disciples were hungry, and they began to pluck heads of grain and to eat," Matthew 12:1 RSV; note that Jesus was not working on the Sabbath - He was merely eating a necessary meal because He was hungry).
"When you make a vow to The Lord your God, you shall not be slack to pay it; for The Lord your God will surely require it of you, and it would be sin in you. But if you refrain from vowing, it shall be no sin in you. You shall be careful to perform what has passed your lips, for you have voluntarily vowed to The Lord your God what you have promised with your mouth. "When you go into your neighbor's vineyard, you may eat your fill of grapes, as many as you wish, but you shall not put any in your vessel. When you go into your neighbor's standing grain, you may pluck the ears with your hand, but you shall not put a sickle to your neighbor's standing grain." (Deuteronomy 23:21-25 RSV)
Deuteronomy Chapter 24
The Law of God is about rights and responsibilities - individual freedom, but in such a way that it benefited the entire nation. Example: military service was a part of Israelite life, but it did not take precedence over the starting of a family, a practical policy since it might provide a replacement Israelite for the father who might later be killed in war.
"When a man is newly married, he shall not go out with the army or be charged with any business; he shall be free at home one year, to be happy with his wife whom he has taken." (Deuteronomy 24:5 RSV)
Another example: when Israelites harvested their fields, they were to not harvest it entirely and then give to the needy, but rather to leave some of the crop unharvested so that the needy could have the simple human dignity, and personal responsibility, of working for what they received.
"When you reap your harvest in your field, and have forgotten a sheaf in the field, you shall not go back to get it; it shall be for the sojourner, the fatherless, and the widow; that The Lord your God may bless you in all the work of your hands. When you beat your olive trees, you shall not go over the boughs again; it shall be for the sojourner, the fatherless, and the widow. When you gather the grapes of your vineyard, you shall not glean it afterward; it shall be for the sojourner, the fatherless, and the widow. You shall remember that you were a slave in the land of Egypt; therefore I command you to do this." (Deuteronomy 24:19-22 RSV)
Fact Finder: As quoted in the verses above, Jesus Christ harvested a small amount of grain on the Sabbath for a needed meal. Some accused Him of violating the Sabbath. How do we know that He didn't?