Fusion systems on metacyclic 2-groups

Let P be a finite metacyclic 2-group and F a fusion system on P. We prove that F is nilpotent unless P has maximal class or P is homocyclic, i.e. P is a direct product of two isomorphic cyclic groups. As a consequence we obtain the numerical invariants for 2-blocks with metacyclic defect groups. This paper is a part of the author’s PhD thesis.