 Complete the following phrase:  In the south, the Soviet plan did not work as effectively and the contingency plan had to be put into effect. The German formations succeeded in penetrating all three Soviet defence belts. This denied the Soviets the opportunity to pin them down in the tactical defence belts and release their operational reserves to engage the enemy on favourable terms. Instead, operational forces for Operation Polkovodets Rumyantsev that were intended for the southern counteroffensive, were ordered to at and near Prokhorovka. This led to the 