Great and powerful are here the results everywhere, but such events are not common in history if we do not confuse with them cases in which a State, for want of activity and energy (Saxony 1756, and Russia, 1812), has not completed its preparations in time.
Now there still remains an observation which concerns the essence of the thing.

A surprise can only be effected by that party which gives the law to the other; and he who is in the right gives the law.

If we surprise the adversary by a wrong measure, then instead of reaping good results, we may have to bear a sound blow in return; in any case the adversary need not trouble himself much about our surprise, he has in our mistake the means of turning off the evil.

As the offensive includes in itself much more positive action than the defensive, so the surprise is certainly more in its place with the assailant, but by no means invariably, as we shall hereafter see.

Mutual surprises by the offensive and defensive may therefore meet, and then that one will have the advantage who has hit the nail on the head the best.
So should it be, but practical life does not keep to this line so exactly, and that for a very simple reason.