I read through a very interesting discussion on this post about the debate on whether Porus or Alexander won the battle. Here are some facts I have read myself on the entire thing -
1) Alexander's exploits were mainly documented by Plutarch, Arrian and some others who were historians living at least 200 yrs after the death of Alexander. They collected stories by speaking to the generals related to Alexander's army and their descendants to write their account.
That brings up a question about the accuracy and exaggeration/moderation of the exploits of Alexander - we cannot believe it cent percent as per text and must try to separate the logical from the exaggerated bits.
For Arrian writes that we must think Alexander as a God. So there is a lot of Greek sentimentalism and devotion mixed in this account which makes it not completely dependable. In Iran and many places of modern persia, he is never called Alexander the great but Alexander of Macedonia. It is because Alexander is accused of having destroyed a lot of their old cultural places and texts etc in his conquests. But after a conquest, Alexander was clever enough to know that a stable empire needs to integrate - so he encouraged the mixing of the west and east via cultural exchange and marriage.
That aside, Alexander was truly a genius of war for his times. His tactics are truly legendary. And this is why I come to the next point.
2) The idea that Alexander retreated from India because of the revolt of his homesick soldiers is still debatable - accounts tell us that Alexander was clever enough to not charge into every battle with the same soldiers. He had a clever rotational system in his army by which after every interval of some time, some groups of men were sent home with women and riches while fresh troops from Macedonia and other conquered places joined his army. Thus, there is no question of his army being homesick!
Then how does a revolt occur, we might ask?
Well, here is my conjecture. Chanakya was already using people to spread rumours in Alexander's army about the scary elephants and black magic practised by the mysterious Indians. To outsiders, our ascetics practising yoga by hanging from the trees or doing a yagna infront of a fire would seem like black magic indeed. And Macedonians were alarmed by black magic as goes history by their reaction to how Olympia worshipped her god.
Moreover, after the battle (forget who wins or loses at the moment) the two kings met and Porus is said to have been asked about what lay further east. Porus told them about the huge army of Magadha with thousands of men and cavalry and elephants. If anything, the thousands of elephants bit is bound to have scared them as just 85 elephants of Porus caused great damage to their army. Question - Was it a strategy of Porus the intelligent statesman to make sure his words intimidated the enemy?
3) After the battle, we find Alexander returning Porus his kingdom and also giving him additional territories. This is something he never did for any other king as far as I know because Porus was not the only honourable king he defeated and then killed. By common sense, only a victor or someone with the upper hand walks away from a war with both his life and kingdom plus extra land to boot.
4) After the battle, the Macedonians travelled south along the river until they reached the coast and then turned west. Question is why would a conqueror who wanted to win the world, dreamt of winning India/Aryavrat of the time promptly turn away after that one fierce battle? Alexander was a great statesman and strict general to his soldiers - as we have disproved the homesickness theory, we have to ask could not Alexander control his men and order them to march ahead to secure his dream?
Logic states that after the fierce battle where his army is accounted to have suffered heavy losses if Alexander won the battle, his men are either afraid of more losses OR if Alexander lost the battle or it was a stalemate, his men are afraid of losing what little life they have left.
But if he won the battle, it should have motivated his army to move ahead. There is no greater motivator than a victory. But they do not move further east but go south instead towards gujarat coast.
Question is why. My logic says that either the Macedonians lost or they arrived at a stalemate against Porus. A stalemate means that Porus's forces ensured that even if they did not win, they dealt so much damage that any victory won by Alexander would produce no positive rewards. In short, the battle probably stopped when both camps realized that neither party was walking away from the place alive and happy. Both sides must then have met and struck a truce. Alexander would not attack Porus, and would give him more land in exchange for his friendship/calling off the war. As by accounts, we know that the overture of peacetalks came from the Macedonian side, as porus was initially ready to fight and die and not sit to talk.
Logic states that Greek historians would not be so praising of Porus' valour if he had not at some point become friendly with their people.
5) Interesting fact is why does Alexander not take the known route he took to come to india...but he takes a new and dangerous route rife with more enemies and battles - logic states that there must have been some obstacle to the army returning by the route they had come...I believe in the stalemate theory. A army cannot march thorugh a place if they have not conquered it. Something must have blocked their way back and forced them to journey southwards. The only army to do so logically becomes the Pauravas who by my logic had won those territories back from Alexander in the truce pact they agreed upon.
These are my views on it. This is probably why even the American movie Alexander (unbiased by greek or indian perspective) did not show the result of that battle. Alexander is shown injured and carried away from the battle, sees the damage and then he gets up later and declares that they should go home now.
In my opinion, whatever be the outcome of that battle, Alexander was forced to abandon his dream halfway in either case.