The successors of Obelerio inherited a united Venice. By the "Pax Nicephori" (803), the two emperors had recognised Venetian "de facto" independence, while it remained nominally Byzantine in subservience. During the reigns of Agnello Participazio (c. 810-827) and his two sons, Venice grew into its modern form. Around 810, Agnello moved the ducal seat from Malamocco to an island of the Rivo Alto group close to the family's property near the Church of Santi Apostoli, near the eastern bank of the Grand Canal, after Pepin, the Frankish king of Italy, attacked Malamocco but failed to invade the lagoon. This marked the beginning of the urbanisation of the islands of the Rivo Alto group, heart of the modern city of Venice. Agnello's dogeship was marked by the expansion of Venice into the sea through the construction of bridges, canals, bulwarks, fortifications, and stone buildings. The modern Venice, at one with the sea, was being born. Agnello was succeeded by his son Giustiniano, who brought the body of Saint Mark the Evangelist to Venice from Alexandria and made him the patron saint of Venice.