The North American P-51 Mustang remains one of the most famous and recognizable aircraft in the world to this day. Nimble and fast -- qualities that led the Mustang to be used even today in air races -- the aircraft was forged in battle. The early Mustangs, often referred to as "Razorback Mustangs", were the first of the type to be built and helped stem the tide of Axis aggression in WWII. This, the first of two volumes on this iconic aircraft, explores the early P-51s. The history of this iconic aircraft is presented through carefully researched archival photographs, as well as photographs of preserved examples, thereby illustrating not only the combat use of the Mk. I, A, B, and C P-51 models, but also the details of its design and construction. Large, clear photographs, coupled with descriptive and informative captions, put the reader on the airfield and in the sky with this historic aircraft.