To survive,it's not necessary to fight(although those that do tend to grow by conquest),but just to be able to defend the society from attack.The Swiss have avoided fighting in the world wars by refusing to take sides,and also being ready to fight.All the men are trained to fight,and they have stockpiles of weapons everywhere.
Planes and tanks are hidden in secret place sin the mountains like some tv adventure series,and all the army movies.Fighters are sent to war to fight for Germany,the captain orders the men to get battle ships ready for attack.They would always make strategies to win the fight,so they might swim under water dig under ground.
Society's which combine both these techniques don't even better.A group which has a small,highly trained army,but most whose members are builders artisans will do better than groups where all members fight but not properly trained.
