This paper shows that ice interaction forces and energies can be related to the characteristics of ice such as strength, stiffness and rheological properties on the one hand, and to the parameters of the impact such as impact velocity, confinement and size of the contact area on the other hand. Mohr-Coulomb relationships are used to evaluate quasi-static loads. Initiation of cracks in ice at the end of the elastic regime is part of this process. Once initiated, the cracks in the ice in their turn affect pressures at ultimate failure of ice. This process has been related to the size of the loaded area by using fracture mechanics. Dependence on strain rate has been applied. The direct effect of collision speed has received special treatment.