The P-51 played a pivotal role in WWII by virtue of its capability to successfully escort American bombers deep into Europe. Prior to the introduction of the P-51, American bomber groups had to fly the last leg of their missions without fighter escorts, and, as such, had served as target practice for German Messerschmitts. (A detailed history of the P-51 Mustang is here.)
If you are at all interested in the World War II and the valor of the men who stepped into such machines to fly into enemy territory and possibly have to go one-on-one with an enemy fighter pilot, take a look at this amazing hi-def photo of the inside of the cockpit of a P-51 Mustang. Please give it time to fully load in order to see the photo in full color and to use the features permitting an up-close and 360-degree view of everything in the cockpit. (You can see one fly and listen to the sound of its engine here.)
I am in awe of such machines and the men who flew them.
Thanks to Jumpmaster Lou for the link.