Deploy the whole army in a line formation but keep mobile strike forces on both ends.This is actually a two headed snake.If the enemy attack one head, use the other head to flank the enemy.If the enemy is trying the center, use both heads to flank them.

Use this formation for standard deployment. This formation also divides your army to three groups with three divisions in each group. One way to use this formation is to shift the whole army to one side and use one of your army group as a flanking force. To make this work, the other two groups of your army need to be able to hold the line long enough for your flanking force to begin collapsing the enemy line from the side.