A highly pertinent FACT that you must not allow to escape you when doing any study of the Koran is that THE EARLY parts are the MOST "Sacred" and venerated to the cult. Those parts that came later, and are more moderate, are looked on as window dressing, and quite unimportant. Consequently, many look on those as demonstrating "religion of peace" statements, and the Islamists take advantage of that misconception.
You have it reversed. The early part of Koran is peaceful (Mecca)
The latter part is full of Islamic war, barabarism and aggression (Medina)