One interesting point is that Philip never needed to mobilise his full military forces, either Macedonian or allied. Page 10:
This though was something I did not know about Siwah:The greatest resource of Macedonia was probably its population...The Macedonian infantry under arms in 334 BC numbered 27,000, and there were ample reserves that could be mustered in subsequent years. The cavalry also was numerous and of high calibre - something over 3,000 at the time of Philip's death. These numbers are formidable, and they comprise only the nucleus of Philip's military resources: his native Macedonian forces...Indeed it can be argued that Philip never need to mobilise more that a fraction of the forces at his disposal.
Alexander could well have visited this temple long before reaching Egypt's temple.The god (Ammon) and his cult were familiar were, however, familiar in the Greek world,... its oracles celebrated and respected. There were also offshoots in mainland Greece, the most famous at Aphytis in Chalcidice, where there was a temple of Zeus Ammon, built in the second half of the fourth century, and whose coinage long before Philip's reign depicted the Libyan god complete with ram's horns. Alexander must have known of the cult since his infancy...
If you are looking for something to read, I would recommend this book. Bosworth clearly had a great enthusiasm for Alexander's adventures, and despite the scholarly content, manages to convey the excitement of the campaign. For example, this simple sentence manages to convey the 'game-on' anticipation of the upcoming battle:
And this dramatizes the crucial moment at Gaugamela:Accordingly he moved up his army to a base camp below the northern outliers of the Jabal Maqlub, where he deposited his baggage and non-combatants, and in the course of the following night he took his fighting force across the intervening hills.
So, did Bessus cause the Persian defeat at Gaugamela by allowing the gap to develop? And did Alexander realise that Bessus was thus defeatable in pursuing him?On the Persian side there was an increasing movement left by the Bactrian units under Bessus, until finally a gap developed between the Persian left and the rest of the line. This was a climatic moment. Alexander was now at the head of a wedge, the Companions thrown forward obliquely with the phalanx continuing the line on one side, the Agrianians and the infantry flank guard receding on the other.... This apex now drove into the gap in the line, and progressively widened it. The Companions then pressed inward, driving at the exposed flanks of the Persian troops while the phalanx in close formation rolled the front line with its hedge of sarisae.
Anyway, another thing that I didn't realise was the Companions' cavalry engagement during the pursuit of Darius was when they were actually returning from the abandoned chase. It is usually portrayed as being during the chase, rather than after it:
As the Companions returned from the pursuit, they crossed the path of a large body of stragglers from the left of the Persian line, the Persians, Parthyaeans and Indians, who had probably retreated in the face of the Macedonian phalanx. They were riding in deep formation and clashed frontally with the returning Companions, who barred their line of retreat. The result was one of the most savage melees of the day, in which some sixty Companions fell.