12 The one item you need is always in short supply.
13 Interchangeable parts aren't.
14 It's not the one with your name on it; it's the one addressed "to whom it may concern" you've got to think about.
15 When in doubt, empty your magazine.
16 The side with the simplest uniforms wins.
17 Combat will occur on the ground between two adjoining maps.
18 If the Platoon Sergeant can see you, so can the enemy.
19 Never stand when you can sit, never sit when you can lie down, never stay awake when you can sleep.
20 The most dangerous thing in the world is a Second Lieutenant with a map and a compass.

More Murphy's Laws of Combat:

#1-11