Deuteronomy 20:7Meaning & Commentary from the Church Fathers

A man who has taken a wife and cultivated a vineyard, much like a parent raising children, is not permitted to engage in battle, as one dedicated to a wife cannot serve in the host of the Lord.

If a man has recently constructed a home but has not yet moved in, or has established a new vineyard but has not yet gathered its produce, or has become engaged to a woman but has not yet wed her, the law of human affection stipulates that such individuals should be relieved from military duty. This reasoning is sound from a military perspective, for if one is driven by personal desires, they may not fight with full commitment (those who enter the fray of battle must approach it unburdened by passions). Moreover, it is also just in a human sense, as the Law, acknowledging the unpredictable nature of warfare, deemed it unfair for one to forfeit the rewards of their labor while another benefits without effort.