Such requisitions, often intolerably burthensome to those upon whom they were laid, must have tended greatly to relieve the strain upon their own resources, which the sustentation of such enormous hosts as the Persian kings were in the habit of moving, cannot have failed to produce in many cases.
The effectiveness of these various arrangements for the provisioning of troops upon a march was such that Persian armies were rarely, if ever, in any difficulty with respect to their subsistence.

Once only in the entire course of their history do we hear of the Persian forces suffering to any considerable extent from a want of supplies.

According to Herodotus, Cambyses, when he invaded Ethiopia, neglected the ordinary precautions and brought his army into such straits that his men began to eat each other.

This caused the total failure of his expedition, and the loss of a great proportion of the troops employed in it.

There is, however, reason to suspect that, even in this case, the loss and difficulty which occurred have been much exaggerated.
The Persians readily gave quarter to the enemy who asked it, and generally treated their prisoners of war with much kindness.