After the victory, Alexander did not make a rush into the heart of the Persian empire, as might have been expected, but rather persisted in his gradual approach of securing coastal areas. Though Alexander continued to break down the Persian fleet, his strategy also gave Darius time to raise a larger army.
Darius also made a first attempt to achieve a peaceful settlement. Although the tone of his letter was arrogant, he offered to cede a significant portion of Asia Minor to Alexander. The concession was difficult to refuse, as the offered area had probably been the objective of Philip's campaign. When Alexander read the letter to his officers, therefore he omitted the section that included the offer. The offers, who heard only Darius's arrogant tone, urged Alexander to continue with the campaign. Alexander sent back a harsh reply justifying the Macedonian mission. It became evident to all that the war would have to come down to a final showdown for the kingdom.
In the meantime, Alexander began his march into the Phoenician territory, where every city-state was under the rule of Persia, but almost all reluctantly. Many cities forced their Persian puppet rulers to surrender to the Macedonians. Alexander replaced the rulers with popular successors, thereby winning himself significant local support.
The one city that chose to oppose Alexander was Tyre, which had long been faithful to Persia and had been the only Phoenician city not to participate in the revolt of the 340s B.C. The Tyrians put up such a strong fight that Alexander succeeded only after seven months, after recruiting ships from Sidon to fend off the Tyrian fleet. The main difficulty, however, was the strength of Tyre's heavily guarded city wall.
Alexander caught a break only when the Tyrians, exhausted and low in morale, took a gamble and launched a surprise sea attack. By luck, Alexander had not been in the location of the attack as the Tyrians had assumed he would be. He was able to round up his ships and catch the Tyrians from the rear. At this point it was only a matter of time before the wall of Tyre was breached. Once again, the slaughter was ruthless. Almost no males were spared; the women and children, numbering 30,000, were sold into slavery. The siege, which finally came to its end in July 332 B.C., is considered, from a purely military standpoint, to be Alexander's greatest achievement.
The victory at Tyre, combined with successful resistance to Persian counterattacks, led to Darius's second offer of peace. He offered 10,000 talents for the release of his family and even more territory. He also invited Alexander to marry his daughter and become the friend of the Persian royal house. More confident after the siege of Tyre, Alexander read the letter to his officers. Despite Parmenion's advice, Alexander refused to negotiate, and instead replied with another harsh letter.