Alliteration

Al·lit·er·a·tion

Alliteration

n.
  1. The repetition of the same letter at the beginning of two or more words immediately succeeding each other, or at short intervals; as in the following lines: -
    Behemoth, biggest born of earth, upheaved His vastness.
    Fly o'er waste fens and windy fields.
    In a somer seson whan soft was the sonne, I shope me in shroudes as I a shepe were.