This band of armed Mexican assailants were just attacking some UNARMED National Guard unit that some lazy Americans refused to attack.
Heck we should be thankful this occurred. Why if it wasn't for these ARMED Mexican invaders, those NG guys prolly wouldn't have gotten their PT done that day. This way they got some running in when they were compelled to retreat.
You can be sure that if the NG's were armed, and killed a couple of the scumbag SOB drug/shitbags, they would be charged with murder.