why did Alexander Army Retreat and did not attack in Empire?
Answers
According to the Greek Sources, Alexander's Army , after their pyrrhic victory over the Porus Army, had their own fears regarding the ongoing Indian campaign.
The most fearsome factor that adversely affected their morale was this
‘…..East of Porus's kingdom, near the Ganges River (the Hellenic version of the Indian name Ganga), was the powerful Nanda Empire of Magadha and Gangaridai Empire of Bengal. Fearing the prospects of facing other powerful Indian armies and exhausted by years of campaigning, his army mutinied at the Hyphasis River (the modern Beas River) refusing to march further east’
Indian campaign of Alexander the Great
This condition was further exacerbated by
1. The Wet Tropical Climate of the Indian Subcontinent which the Greeks were very uncomfortable and made them vulnerable to tropical Diseases.
2. Battle with a mere local kingdom resulted in heavy losses [ Alex himself suggested that his Battle with Porus was the toughest he fought] and the prospects of war with a major empire certainly hit the morale of his troops.
3. His soldiers knew a gargantuan army was waiting for them across the Ganga River which had numerical and logistic advantage.
In these conditions, Alexander was probably wise enough to use the Soldiers' Rebellion as a cause to retreat from India as he might have known the consequences of such misadventure.