Here is a pic

As I do not have the orcish near, I took the araby for the example agains some ratmen.
I suppouse is turn of araby and the general is near.
First the blue order. Infantry attack, by iniciative or by one order.
Then red order. It is very probable to succed the order. I assume the light cavalry is 20cm to enemy but could be far of 20cm and then they do not have the -1. The only thing important is they should finish at 15cm or less in the enemy flank.
Then the white order. Now it is difficult to happen, second order, proximity and it is very probable the general is far away 20cm or even 40+cm. But this las order is not very important because they are light cavalry. If the order succed they horsemen charge to the side of ratmen. But if they fail they can shoot (6 shots) to the ratmen swordmen. It is proabable that those ratmen swordmen are driven back denying the support to the charge of arab lancers.
If you do the same with heavy cavalry instead light cavalry then the white order must happens or your strategy will fail. Even if the white orders fails you are exposing your knights for nothing deep in the enemy battleline.
Laght cav as they see all around does not need even to be in the same situations as in the pic (looking to the ratmen) exposing their flank to the enemy battline. They could be slightly diagonal, presenting front to the enemy battleline but seeing 360º and able to shoot or charge to the ratmen swordmen