Let be an algebraically closed field. Let be a vector space equipped with a non-degenerate symmetric or symplectic bilinear form B over . Suppose the characteristic of is sufficiently large, i.e. either zero or greater than the dimension of . Let denote the group of isometries. Using the Jacobson–Morozov lemma we give a new and simple proof of the fact that two elements in are conjugate if and only if they have the same elementary divisors.