Okay, moving away from Asian martial arts and looking towards Europe; here is a small scale model of how a column worked in a Roman formation. Obviously a formation would have several columns of soldiers, this is just a cross section of a single column within a formation (hence why the enemy aren't trying to outflank them).

So the idea of a Roman column is to have a row of soldiers where the soldier at the very front of the column will fight the enemy. This will obviously begin draining the soldier's energy level.


After about a minute or so, an officer will sound a signal.


Upon hearing this signal, the soldier at the front will step to the left and walk down to the rear of the column. The soldier behind him immediately steps forward to take his place fighting the enemy, and also to allow the formation to advance. The next soldier will often step over the bodies of slain enemy combatants.


The first soldier rests and regains his energy while his replacement fights on.


Then after about another minute the signal is sounded again for the third soldier to assume front rank and the column marches forward, gaining ground.


This...


...continues...


...allowing the Romans to continually exhaust the enemy...


...while they appear inexhaustible to the enemy because of a steady rate of replenishing troops.


Should a Roman soldier fall in battle...


...then the next fully charged soldier takes his place while a reservist is placed at the rear of the column to replace the one that was lost.