Alexander’s invasion to persia

You will present for 5-10 minutes your answer to the question: What was the most distinctive and unique aspect of Alexanders career and policies, as described by our sources?
My topic: Alexander’s invasion of Persia

Professor will be grading on a reasonable argument (30%) and demonstration of knowledge of course content (70%).

For this, I need a proper reference from an ancient source with 4 slides to present and 1 page of speech for the later part.