Shortly after the battle, Memnon died. His replacement was a Persian who had spent time in Macedonia called Pharnabazus. He disrupted Alexander’s supply routes by taking Aegean islands near the Hellespont and by fomenting rebellion in southern Greece. Meanwhile, Darius took the Persian army to intercept Alexander.
Alexander marched his army east through Cappadocia, where, for a stretch of nearly 150 km (93 mi), there was no water. As his army approached Mount Taurus, they found only one route through which to pass, which was a narrow defile called “The Gates”. The defile was very narrow, and could have been easily defended. However, the Persian satrap of Cappadocia had an inflated view of his own abilities. He had been at the Battle of the Granicus River, and had believed that Memnon’s scorched Earth strategy would work here. He didn’t realize that the different circumstances of the terrain made that strategy useless. Had he mounted a credible defence of the defile, Alexander would have been easily repulsed. He left only a small contingent to guard the defile, and took his entire army to destroy the plain that lay ahead of Alexander’s army. The Persian contingent that was supposed to guard the defile soon abandoned it, and Alexander passed through without any problems. Alexander supposedly said after this incident that he had never been so lucky in his entire career.
After reaching Mount Taurus, Alexander’s army found a stream that flowed from the mountain with water that was ice cold. Not thinking, Alexander jumped into the stream, suffered a cramp and then a convulsion, and was pulled out nearly dead. He quickly developed pneumonia, but none of his physicians would treat him, because they feared that, if he died, they would be held responsible. One physician named Philip, who had treated Alexander since he was a child, agreed to treat him. Although he soon fell into a coma, he eventually recovered.
Source: Wikipedia
