no plan survives contact with the enemy

phrase2

1. •
   After a plan against an enemy is drafted, there will be unexpected elements from the opposition that will call for improvisation.
2. •
   Even with a preexisting plan, unexpected circumstances will require one to think on one's feet.

   • ‹"No plan survives first contact with the enemy." Or with a pretty girl in a sundress.› — 2015