[elygre]

I looked at that page before writing my comment.

It says that perfidy is a war crime. However, I don’t see anything supporting summary execution.

https://en.m.wikipedia.org/wiki/Summary_execution says the following:

“Francs-tireurs (a term originating in the Franco-Prussian War) are enemy civilians or militia who continue to fight in territory occupied by a warring party and do not wear military uniforms, and may otherwise be known as guerrillas, partisans, insurgents, etc. Though they could be legally jailed or executed by most armies a century ago, the experience of World War II influenced nations occupied by foreign forces to change the law to protect this group.”

[bandrami]

Sorry I hadn't read the whole thread: I agree the "false colors" sense of perfidy generally is granted due process. I was thinking of the "feigning surrender" sense of perfidy, which is pretty much universally met with summary execution.