The Quran is very clear on this subject, that monogamy is the basis for normal relationships, while polygamy is only allowed in cases involving marrying the mothers of orphans and/or orphan woman so that they are taken care of. A maximum of four wives is allowed in such cases.
For example, in the aftermath of the war, it is likely that many men would have lost their lives, resulting in many widows with fatherless children, thus The Quran allows an exception in these cases so that the needs of the wider community can be met:
Give the orphans* their money; do not replace the good with the bad, and do not consume their money to your money, for truly it is a great sin!
And if you fear that you cannot be just to the orphans, then you may marry those who are agreeable to you of the women: two, and three, and four. But if you fear you will not be fair, then only one**, or to whom you are committed to by oath. This is best that you do not face financial hardship. [4:3]
*the Arabic word for "orphans" is "yatama" and specifically means children who are fatherless. ** note the emphasis on one wife, i.e. monogamy.
Again, the subject of polygamy is addressed in the context of orphans:
They ask you for divine instruction concerning women. Say, "God instructs you regarding them, as has been recited for you in the book about the women orphans who you want to marry without giving them what has been ordained/written for them, as well as the powerless children, and your duty to treat orphans with equity. Whatever good you do; God has full knowledge of it. [4:127]
The above verse has been commonly mistranslated to justify marrying orphan girls rather than marrying orphan women. The Arabic plural pronoun in this verse is the female form, "allatee" (not the male form "allazyna"), and it can only refer to the women just referenced, not to the orphans. This is because in Arabic the word "yatama" (orphans) is grammatically male in gender. The beginning of the verse also tells us the subject of the verse: it is about the women. Further, the Arabic word used here is "nisa" and means "women" not girls.
It is important to remember all translations are imperfect and to seek knowledge and verify the information for oneself [17:36].
Again, The Quran shows a preference for monogamy in the following verse:
And marry the single from among you as well as the good from among your male and female servants. If they are poor, then God will grant them from His grace. God is Encompassing, Knowledgeable. [24:32]
To summarise, The Quran was revealed to a society where polygamy was a commonplace, and men could have many wives (e.g. more than four for example). By setting an upper limit, citing a moral restriction on polygamy, and limiting the situations in which it is allowed would result in reducing polygamy significantly.