History of the Republic of Venice of the Sea" ceremony was established in this period. Orseolo died in 1008. Venice's control over the Adriatic was strengthened by an expedition by Pietro's son Ottone in 1017, by which time Venice had assumed a key role in balancing power between the Byzantine and Holy Roman Empires. During the long Investiture Controversy, an 11th-century dispute between Henry IV, Holy Roman Emperor and Pope Gregory VII over who would control appointments of church officials, Venice remained neutral, and this caused some attrition of support from the Popes. Doge Domenico Selvo intervened in the war between the Normans of Apulia and
Gulf of Tadjoura Gulf of Tadjoura The Gulf of Tadjoura (), () is a gulf or basin of the Indian Ocean in the Horn of Africa. It lies south of the straits of Bab-el-Mandeb, or the entrance to the Red Sea, at . The gulf has many fishing grounds, extensive coral reefs, and abundant pearl oysters. Most of its coastline is the territory of Djibouti, except for a short stretch on the southern shore, which is part of the territory of Somalia. The Gulf other marine habitats include sea grass beds, salt pans and mangroves. In August 1840, the conclusion of a treaty