It was intentional, or so the rumors now go. He used distortion, whammy (to bend notes and generally make the music chaotic) and wailing notes in an intentional manner to attempt to make the anthem sound like the war/Vietnam, and do his best to have the guitar playing be reflective of gunfire and bombs going off. It wasn't supposed to sound pretty or melodious. Personally, as a pretty capable guitarist of ~20 years, I have a difficult time replicating his version perfectly (though I do use his version, skipping over the chaotic parts and retabbing certain areas of his version, to play a more normal/recognizable version of the anthem)
It was intentional, or so the rumors now go. He used distortion, whammy (to bend notes and generally make the music chaotic) and wailing notes in an intentional manner to attempt to make the anthem sound like the war/Vietnam, and do his best to have the guitar playing be reflective of gunfire and bombs going off. It wasn't supposed to sound pretty or melodious. Personally, as a pretty capable guitarist of ~20 years, I have a difficult time replicating his version perfectly (though I do use his version, skipping over the chaotic parts and retabbing certain areas of his version, to play a more normal/recognizable version of the anthem)