“If you go to war against your enemy.” RASHI interprets that this means optional war.
We should understand that this implies that there are two types of war: 1) over actions, meaning doing Mitzvot [commandments] or transgressions, 2) over permission, meaning that all the observing of Torah and Mitzvot is in order to expand man’s authority, to have more possessions each time, or over annulling of authority, when he wants to achieve the annulment of his own authority by means of observing Torah and Mitzvot, and that the authority of the Creator will expand instead so there will not be multiple authorities, but a singular authority.
“Multiple authorities” means that he extracts from the authority of the Creator into his own authority, and “singular authority” means that he annuls his own authority and wants only the authority of the Creator to exist. This is regarded as achieving a degree where all his desires are in order to bestow.