Which is why disguising your soldiers as civilians or part of the enemy army has been forbidden by every war treaty under the sun and soldiers caught under such circumstances are treated as spies rather than POW's. Which is another way to say "summarily executed".Apparently, the easiest way to win a war is to use plainclothes guerillas because, unless your enemy is super lucky or super insightful, they will either:
a) miss those disguised soldiers allowing for much easier infiltration
b) end up killing civilians thinking that they are disguised troops, resulting in war crimes.
relevant Geneva Convention
Article 37. – Prohibition of perfidy
1. It is prohibited to kill, injure or capture an adversary by resort to perfidy. Acts inviting the confidence of an adversary to lead him to believe that he is entitled to, or is obliged to accord, protection under the rules of international law applicable in armed conflict, with intent to betray that confidence, shall constitute perfidy. The following acts are examples of perfidy:
(a) The feigning of an intent to negotiate under a flag of truce or of a surrender;
(b) The feigning of an incapacitation by wounds or sickness;
(c) The feigning of civilian, non-combatant status; and
(d) The feigning of protected status by the use of signs, emblems or uniforms of the United Nations or of neutral or other States not Parties to the conflict.
2. Ruses of war are not prohibited. Such ruses are acts which are intended to mislead an adversary or to induce him to act recklessly but which infringe no rule of international law applicable in armed conflict and which are not perfidious because they do not invite the confidence of an adversary with respect to protection under that law. The following are examples of such ruses: the use of camouflage, decoys, mock operations and misinformation.
Article 38. – Recognized emblems
1. It is prohibited to make improper use of the distinctive emblem of the red cross, red crescent or red lion and sun or of other emblems, signs or signals provided for by the Conventions or by this Protocol. It is also prohibited to misuse deliberately in an armed conflict other internationally recognized protective emblems, signs or signals, including the flag of truce, and the protective emblem of cultural property.
2. It is prohibited to make use of the distinctive emblem of the United Nations, except as authorized by that Organization.
Article 39. – Emblems of nationality
1. It is prohibited to make use in an armed conflict of the flags or military emblems, insignia or uniforms of neutral or other States not Parties to the conflict.
2. It is prohibited to make use of the flags or military emblems, insignia or uniforms of adverse Parties while engaging in attacks or to shield, favour, protect or impede military operations.
3. Nothing in this Article or in Article 37, paragraph 1(d), shall affect the existing generally recognized rules of international law applicable to espionage or to the use of flags in the conduct of armed conflict at sea.