Right now I am listening to Steven Pressfield's "Virtues of War" and he mentioned something in yesterday's session that I had not considered. I had read in a number of sources that the Macedonians bitterly resented the incorporation of Persian units into Alexander's expeditionary force but Pressfield points out that the most politically damaging policy Alexander adopted was the appointment of Persian commanders' sons to his corps of personal pages. The number of pages was apparently fixed and the appointment of Persian youths meant that existing pages from Macedonian royalty had to be dismissed. This was seen as an afront to a number of Macedonian noble familes back home as well as by the youth's relatives already serving in the corps. Furthermore, the Macedonian pages aligned themselves with older officers and commanders who acted as mentors and champions (and possibly lovers). However, these officers would have nothing to do with the Persian boys which resulted in a deficit in their training.
In today's session, Pressfield has Alexander explaining his exasperation with the guerilla warfare he was forced to contend with in what is now Afghanistan. He explains that he broke up the corps into smaller independent fighting units that essentially were sent out on "search and destroy" missions. He found this type of warfare not only demoralizing but devastating to the army's overall unity. The smaller fighting units began thinking of themselves as men of their individual unit commander rather than as part of the overall expeditionary force with loyalty to Alexander. This sounds very much like the problems that developed in the late Roman Republic after Marius' reforms when legions looked to their commanders instead of the senate and people of Rome as the focus of their loyalty and career advancement.