In November 333 BC Darius III had lost the Battle of Issus, resulting in the capture of his wife, his mother and his two daughters, Stateira II and Drypetis. Darius had retreated to Babylon, where he regrouped his remaining army. The victory at Issus had given Alexander control of southern Asia Minor. Following a victory at the Siege of Tyre (332 BC), which lasted from January to July, Alexander controlled the Levant. After his victory at Gaza Persian troop counts were low and the Persian satrap of Egypt, Mazaeus, peacefully surrendered to Alexander.
Negotiations between Darius and Alexander
Darius tried to dissuade Alexander from further attacks on his empire by diplomacy. Ancient historians provide different accounts of his negotiations with Alexander, which can be separated into three negotiation attempts.
Justin, Arrian and Curtius Rufus write that Darius sent a letter to Alexander after the Battle of Issus. It demanded that he withdraw from Asia and release his prisoners. According to Curtius and Justin he offered a ransom for his prisoners, but Arrian does not mention a ransom. Curtius describes the tone of the letter as offensive. Alexander refused his demands.
A second negotiation attempt took place after the capture of Tyre. Darius offered Alexander a marriage with his daughter Stateira II and all the territory west of the Halys River. Justin is less specific, not mentioning a specific daughter and speaking of a portion of Darius' kingdom. Diodorus Siculus likewise mentions the offer of all territory west of the Halys River, a treaty of friendship and a large ransom for the captives. Diodorus is the only ancient historian who mentions that Alexander concealed this letter and presented his friends with a forged one favorable to his own interests. Again Alexander refused.
Darius started to prepare for another battle after the failure of the second negotiation attempt. Even so, he made a third and final effort to negotiate after Alexander's departure from Egypt. Darius' third offer was much more generous. He praised Alexander for the treatment of his mother Sisygambis and offered him all territory west of the Euphrates, co-rulership of the Achaemenid Empire, the hand of one of his daughters and 30,000 talents of silver. In the account of Diodorus, Alexander deliberated this offer with his friends. Parmenion was the only one who spoke up, saying, "If I were Alexander, I should accept what was offered and make a treaty." Alexander reportedly replied, "So should I, if I were Parmenion." Alexander again refused the offer of Darius, insisting that there could be only one king of Asia. He called on Darius to surrender to him or to meet him in battle to decide who was to be the sole king of Asia.
The descriptions given by other historians of the third negotiation attempt are similar to the account of Diodorus, but differ in details. Diodorus, Curtius and Arrian write that an embassy was sent instead of a letter, which is claimed by Justin and Plutarch. Plutarch and Arrian mention the ransom offered for the prisoners was 10,000 talents, but Diodorus, Curtius and Justin give a figure of 30,000. Arrian writes that this third attempt took place during the Siege of Tyre, but the other historians place the second negotiation attempt at that time. With the failure of diplomacy, Darius decided to prepare for another battle with Alexander.