Well from Washington crossing the Deleware River to attack drunk Hessians, the Tet Offensive, or even the Trojian Horse attack--Attacking while the others are celebrating is as old as written history. One reason why the commies are even more successful at this like TET or others, is they do so on a grande scale even in places they haven't started shit before, way behind the front lines.

Cancel those 3 day passes men, lock up the rum rations, and issue extra clips& powderhorns.