In this chapter we solve the main conjugacy problems for unipotent elements of symplectic and orthogonal groups in characteristic 2. Many of the methods of Chapter 4 do not apply: there is no Cayley map between unipotent and nilpotent elements, nor is there a factorization of the centralizer of a unipotent element in a canonical parabolic subgroup. Hence, although we can exploit some features of the good characteristic case, our algorithms are more complicated.