The Pulpit Commentary
The instructions in this chapter are peculiar to Deuteronomy. As the people of God, Israel was not a warlike nation; they were rather to abstain from warfare, and as a general rule to cultivate the arts of peace. But they had before them at this time the prospect of a serious and protracted conflict before they could occupy the land which God had assigned to them; and they might in future years have to go to war to maintain their independence and repel aggression. In view of this, instructions are here given regarding the conducting of military service.

When they found themselves opposed by an army more numerous than their own, and better furnished with the material of warfare, they were not to be afraid or discouraged, for Jehovah their God, who had brought them out of Egypt, would be with them to protect and help them (cf. Psa_20:7). Horses and chariots. In these, which constituted the main strength of the nations with which they would have to contend, the Israelites were deficient; and to them these were always objects of terror in war (Jos_11:4; Jos_17:16; Jdg_1:19; Jdg_4:3; 1Sa_13:5).

The Pulpit Commentary
The priest. Not the high priest or any one of the priests, but the military priest, the priest appointed to accompany the army, "the anointed for the war;" משׁיח המלחמה, as the rabbins designate him (cf. Num_21:6; 1Sa_4:4; 2Ch_13:12). His business was to exhort the people, and to encourage them by reminding them that the Lord was their Leader, and would help them in the conflict. The formula of his exhortation is given in Deu_20:3, Deu_20:4.

The Pulpit Commentary
The officers; the shoterim, the keepers of the genealogical tables (Deu_16:18). It belonged to them to appoint the men who were to serve, and to release those who had been summoned to the war, but whose domestic relations were such as to entitle them to exemption. If there was one who had built a house, but had not dedicated it, i.e. by taking possession of it and dwelling in it; or if there was one who had planted a vineyard and had not eaten of the fruit thereof; or if there was one who had betrothed a wife, but had not yet married her;—such were to be allowed to return home, lest they should die in battle, and it be left to others to consummate what they had begun. According to Josephus, this exemption was for a year, according to the analogy of Deu_24:5. Dedicated; probably formal possession was taken of the house by some solemn ceremony, followed by a festive entertainment. Vineyard. The Hebrew word (כֶּרֶם) here used designates "a field or park of the nobler plants and trees cultivated in the manner of a garden or orchard" (Ges.); so that not vineyards alone, but also olive yards and plots of the more valuable fruit trees may be intended. Hath not eaten of it; literally, hath not laid it open, made it common, i.e. begun to use it, to gather its produce for common use (cf. Deu_28:30; Jer_31:5). Trees planted for food were not to be used before the fifth year of their growth (Le 19:23, etc.; of. Deu_24:5).

The shoterim were also to allow any that were naturally timid and fainthearted to return to their homes, lest, if they remained with the host, others, infected by them, should lose courage and become unfit for service. His brethren's heart faint; literally, flow down or melt (cf. Jos_7:5). In Deu_1:28, this verb is rendered by "discouraged."

The Pulpit Commentary
The next thing the shoterim had to do was to appoint captains to head the people who were going to war. The army was divided into bands or companies, and over each of these a captain was placed, whose it was to command and lead (cf. Num_31:14, Num_31:48; 1Sa_8:12; 1Sa_22:7; 2Sa_18:1). Captains of the armies. The phrase, "captain of a host" (שַׂר צָבָא), usually designates the general or commander-in-chief of the entire army (Gen_21:22; 2Sa_2:8; 1Ki_16:16, etc.); but here the phrase is used in the plural of the chiefs of the companies or detachments of which the whole was composed.

The Pulpit Commentary
Directions concerning the besieging of towns. In the case of a town at a distance, not belonging to any of the Canaanitish tribes, on advancing against it they were first of all to summon the inhabitants to a peaceable surrender and submission (cf. Jdg_21:13). If this was complied with, the inhabitants were to become tributary to the Israelites and serve them; but if this was refused, the town was to be besieged, and, when taken, all the males were to be slain, and the women and children, as well as all the booty that was in the place, were to be taken as the prey of the conquerors, who were to appropriate the spoil to their own use.

Then proclaim peace unto it; i.e. invite it peaceably to surrender.

The Pulpit Commentary
Shall be tributaries unto thee, and they shall serve thee; literally, shall be to thee for tribute and service. The word rendered by "tribute" (מַם) denotes properly tribute service, service rendered as a tribute, whether for a season or in perpetuity (cf. Gen_49:15; Jdg_1:30, Jdg_1:33, Jdg_1:35; 1Ki_5:13; 1Ki_9:21; Isa_31:8 [Authorized Version, "discomfited"])

Shalt eat the spoil; consume it for thine own maintenance.

The Pulpit Commentary
This was for cities at a distance; it was to be otherwise with the cities of the Canaanites. To them no offer of peaceful submission was to be made, and when the city was taken, all the inhabitants without reserve were to be destroyed. This was in accordance with God's command to Israel (Exo_23:31-33; Exo_34:11-16; Deu_7:1-3), and as a precaution against the risk of the people being seduced into idolatry by the heathen should they be allowed to remain in the land. But whilst engaged in besieging a town, they were not to destroy the fruit trees that were outside the walls; but trees that were not for food they might cut down and use in their operations against the city.

To employ them in the siege; literally, to come, i.e. that they should come into the siege before thee, i.e. either as thine adversary or to be used by thee for the siege. For the tree of the field is man's life. This may mean that the tree supplies food for the sustenance of man's life. But as the words stand in the text, they can only be rendered thus: "For the man s a tree of the field." This gives no good sense, or indeed, any sense at all; and hence it is proposed to alter the reading of the text so as to produce a meaning that shall be acceptable. From an early period the expedient has been resorted to of reading the clause interrogatively, and, instead of regarding it as parenthetical, connecting it with the following words, thus: "Is the tree of the field a man to come into siege before thee?" So the LXX; Rashi, etc. It has been thought that only a very slight change in the punctuation is required to justify this rendering (הֶאָדָם instead of הָאָדָם); but more than this is acquired: the subject and object are hereby reversed, and this is more than can be allowed. From an early period also it has been proposed to read the clause as a negation, "For the tree of the field is not a man to come into siege before thee." So the Targum of Onkelos, Abarbanel, Vulgate, etc. The sense here is substantially the same as in the preceding, and the same general objection applies to both. To both also it may be objected that by this way of taking the passage Moses is made to utter a sentiment at once puerile and irrelevant; for what need to declare formally, or in effect, that a tree is not a man? and what reason is there in this for not cutting down fruit trees any more than other trees? In the margin of the Authorized Version an alternative rendering is proposed, "O man, the tree of the field is to be employed in the siege." But admitting this as a possible rendering, it is exposed to the objection, on the one hand, that it is improbable that in a prosaic address like this an explanatory appeal would be introduced; and on the other, that it is inconceivable that Moses would in this casual and startling way anticipate what he goes on in the next sentence to express deliberately and clearly. The passage has probably suffered at the hands of a transcriber, and the text as we have it is corrupt. The sense put upon it in the Authorized Version is that suggested by Ibn Ezra, and in the absence of anything better this may be accepted. The fruit tree is man's life, as it furnishes that by which life is sustained, just as, in Deu_24:6, the millstone is called a man's life, inasmuch as it supplies the means of life.

The Pulpit Commentary
And thou shalt build bulwarks against the city … until it be subdued; literally, That thou mayest build a siege—he, an instrument for besieging, a rampart, or bulwark—against the city, till it come down (cf. Deu_28:52).