Short answer. Only if the marriage is in articulo mortis, meaning at the point of death, not simply because you are present in a conflict area. Family Code Article 32 gives a commissioned military commander authority to solemnize marriages in articulo mortis within a zone of military operation, for civilians or armed forces members alike.
What the law says
A military commander of a unit, who is a commissioned officer, shall likewise have authority to solemnize marriages in articulo mortis between persons within the zone of military operation, whether members of the armed forces or civilians.
Family Code, Article 32 — Marriage in Articulo Mortis by a Military Commander. Read the full provision →
What Article 32 actually authorizes
Article 32 gives this authority in specific terms: a military commander of a unit, who is a commissioned officer, shall likewise have authority to solemnize marriages in articulo mortis between persons within the zone of military operation, whether members of the armed forces or civilians. Two conditions have to be present together: the marriage has to be in articulo mortis, meaning at the point of death, and it has to take place within a zone of military operation. The article extends the authority to civilians as well as members of the armed forces, so being a civilian does not put you outside its reach.
Why 'trapped in a war zone' is not, by itself, enough
Being physically present in an active conflict area satisfies the second condition, the zone-of-military-operation requirement, but it does not on its own satisfy the first. In articulo mortis specifically describes a marriage entered into when one or both parties are facing imminent death, not simply a marriage taking place somewhere dangerous. If neither of you is actually in that condition, a commander invoking this particular article to solemnize your marriage would be doing so without one of the two conditions the text actually requires, whatever the surrounding danger of the location.
What this means for your situation
If you and your fiance are simply present in a war zone without either of you facing imminent death, Article 32's authority for a commander to solemnize an articulo mortis marriage does not describe your circumstances as written. This article is narrow by design, tied to a specific emergency at the point of death, rather than a general grant of authority to marry any civilians a commander happens to encounter in a combat area. Whether some other basis could apply to your situation is a separate question this article does not answer.
Why the word 'likewise' in the article is a clue
Article 32 says the commander shall likewise have authority, which signals that this provision sits alongside other articles granting similar in-articulo-mortis authority to different officials, such as those who solemnize marriages of parties at the point of death outside a military context. The article is one piece of a broader framework the Family Code sets up specifically for marriages entered into when death is imminent, rather than a standalone rule about combat zones. Reading it in isolation, as authority for any marriage a commander performs in a dangerous area, misses the condition the word 'likewise' points back to.