Basil helped the new emperor get rid of Phokas' supporters and relatives. He also assisted in the retirement of Romanos II's and Phokas' widow, Theophano, and advised Tzimiskes to cement his position by marrying Theodora, a daughter of Constantine VII. Under Tzimiskes, Basil played a leading role in the governance of the state, especially in the fiscal administration, while Tzimiskes himself was more concerned with foreign policy and his military campaigns. Basil himself took part in the great campaign against the Rus' in Bulgaria in 971, having been entrusted with the reserve forces, the baggage train and the supply arrangements, while Tzimiskes himself with his elite troops marched ahead.