Islam and War

excerpted from John Keegan's seminal work "A History of Warfare."

  "Muhammad, unlike Christ, was a man of violence; he bore arms, was wounded in battle and preached holy war, jihad, against those who defied the will of God, as revealed to him. His successors view of the world as divided into Dar al-Islam -- the House of Submission, submission to the teachings of Muhammad, collected in the Koran --  and Dar al-Harb, which were those parts yet to be conquered." 
[link to the text]

Muhammad's Conquests

1. Some more academic research on dar al-harb and dar al-Islam can be found in the Ethics and the Use of Force by James Turner Johnson
2. Muhammad as a Warrior