There are certain military principles which must be obeyed in warfare.
-principle of mass
-Concerntrating your forces at the decisive point
-Maintain secrecy/ element of surprise
-Maintain reserve forces
-Keep the high ground
-Enevelopment/ outflank the enemy.
-Counter-attack
-Superiro mobility

I think the first two basically mean the same thing of outnumbering the enemy in a given area to produce quick victories. if this can be replicated many times by an army over an entire front it will acheive many victories whilst incurring relatively low casualties. If i'm not mistaken this principle (in conjunction with envelopment) was what made Blitzkrieg tactics sho successful in early WW2.
Overall what would you say is the best tactic out of all of these. give historic examples where armies have used these principles to good effect.