To prove himself a worthy successor to his father both at home and in the eyes of foreign governments, Peter began his reign with a military offensive into Byzantine Thrace in 927 which was the last campaign of the Byzantine–Bulgarian war of 913–927. Nevertheless, he followed up his quick successes by secretly negotiating a peace treaty before the Byzantine government had a chance to retaliate. The Byzantine Emperor Romanos I Lakapenos eagerly accepted the proposal for peace and arranged for a diplomatic marriage between his granddaughter Maria and the Bulgarian monarch. In October 927 Peter arrived near Constantinople to meet Romanos and signed the peace treaty, marrying Maria on 8 November in the church of the Zoödochos Pege. To signify the new era in Bulgaro-Byzantine relations, the princess was renamed Eirene ("peace"). The extensive Preslav Treasure is thought to represent part of the dowry of the princess. The treaty of 927 actually represents the fruit of Simeon's military successes and diplomatic initiatives, ably continued by his son's government. Peace was obtained with the frontiers restored to those defined in treaties of 897 and 904. The Byzantines recognised the Bulgarian monarch's title of emperor ("basileus", "tsar") and the autocephalus status of the Bulgarian patriarchate, while the payment of an annual tribute to Bulgaria by the Byzantine Empire was renewed.