day no. 15,009: quick and hard, where and when

"“Many years ago, as a cadet hoping some day to be an officer, I was poring over the ‘Principles of War,’ listed in the old Field Service Regulations, when the Sergeant-Major
came up to me. He surveyed me with kindly amusement. ‘Don’t bother your head about all them things, me lad,’ he said. ‘There’s only one principle of war and that’s this. Hit the
other fellow, as quick as you can, and as hard as you can, where it hurts him most, when he ain’t lookin’!’” —Sir William Slim

“Now an army may be likened to water, for just as flowing water avoids the heights and hastens to the lowlands, so an army avoids strength and strikes weakness” —Sun Tzu

As quick as you can.
As hard as you can.
Where it hurts most.
When he ain't looking.

This presupposes a fair fight, meaning both sides know that they are fighting. It is no grand achievement to sucker punch someone who didn't know you were quarreling. However, if the enmity is articulated and agreed upon and both sides know that they are fighting, the advice contained above is a bite-sized battle cry for fighting.

Quick keeps surprise surprising. Hard makes the effort as impactful as possible. Hitting an impenetrable place quick and hard leaves no mark and wears you out. Hitting them where it hurts most, especially if quick and hard, is the best way to exponentially increase the effect of your efforts. When he ain't looking eliminates his ability to subtract any force from the blow, counter attack or discount the amount of force you are using.

All these things combined make for short wars.

So realize that our enemy is looking to employ these principles against us as well. He seeks to be quick and force you to react without thinking. He sends the house in order to take you out in one fell swoop. He aims at your area of weakness and he looks to catch you off guard.

But God has weaponized our weakness

2 Corinthians 12:10-11
But he said to me, “My grace is sufficient for you, for my power is made perfect in weakness.” Therefore I will boast all the more gladly of my weaknesses, so that the power of Christ may rest upon me. 10 For the sake of Christ, then, I am content with weaknesses, insults, hardships, persecutions, and calamities. For when I am weak, then I am strong.

And there is no reason to be caught off guard or to be unprotected.

Ephesians 6:13
Therefore take up the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand firm.