From a speech given by Alexander is to encourage his army to have confidence.
Explanation:
The Alexander's speech is to motivate his army that they can fight as the war this is between the victorious army and with the enemy who was already defeated. Anyways the opponents are going to fight for only the pay but not more than that. He also said to his army that although the danger has come to you, you didn't step back and look forward to winning the war. By these sentences by Alexander, we came to know that the purpose of the speech is to encourage his army to have confidence.
