E=Easterling, C=Captain, B=Banner, 1 space=1 inch.

Starting formation, 4x3 in base contact:
ECEE
EEEE
EBEE

Situation 1: Enemy formation with wider frontage will charge: Your back rank should split and file to the sides, giving you a 6-wide 2-deep formation. Everyone gets 2 attacks, facing only 2 enemy attacks given basic Warriors and spears.

EECEEE
EEBEEE


Situation 2: enemy formation with wider frontage will charge, but you still want 3 Attacks per model (best used against enemies with lower F value, or if you need a bit more staying power)

E C E E
E E E E
E B E E

So in other words, you spread the formation to match their frontage, using Conrol Zones and base sizes to be sure they can still only engage your front rank. 3 attacks per model, with a re-roll, putting you on even terms with 2 Supported enemies.



Situation 3: Enemy formation with lower frontage (typically Elite units) is going to charge, and you are not in danger of being flanked:

ECE
EEE
EEE
EBE

This gives you more staying power in a trade for less killing power; you have a 'spare' Easterling in each file to move up and fill any gaps without losing an Attack. Bit more situational, but if you need to hold on a bit longer, it can work. It also functions as a marching formation if you have distance to cross, as the 'spare' models can fill any gaps caused by Archers.

Of course, this isn't comprehensive, but it gives you an idea of how it works.