the first time ship based helicopters were used and large scale amphibious assaults were made. The assaults against the several islands were supported by naval bombardments and air strikes. For the operation, the Navy employed the frigate Nuno Tristão—that served as the command post for the operation—the destroyer Vouga, seven patrol boats, eight landing craft and three detachments of Special Marines – that, together with a reinforced Army battalion, formed the landing forces. In 1970, the Naval Forces in the Portuguese Guinea perform the secret Operation Green Sea (Operação Mar Verde), a major amphibious raid on Conakry, the capital of the neighboring Republic of Guinea, an open supporter and a sanctuary for the PAIGC. The Operation was led by Lieutenant-Commander Alpoim Calvão, heading task force TG 27–2, composed of the patrol boats Cassiopeia, Dragão, Hidra and Orion and the landing craft Bombarda and Montante, carrying a landing force that included 250 Portuguese Commandos and Special Marines and 150 political opponents of the Guinean dictatorship. During the night of 21–22 November, the Portuguese forces were able to take the control of the city, neutralizing the Guinean Army and the locally based PAIGC forces, destroying several naval and military assets of the PAIGC and rescuing 26 Portuguese POWs that were being held in a local prison. In the theatre of Mozambique, the main operational focus of the Portuguese Navy was the Lake Nyasa, in an effort to deter FRELIMO forces infiltrations from their bases in Tanzania and to cooperate with the Military of Malawi. This mission was done by the Nyasa Flotilla, operating mainly from the Metangula naval base, and by units of marines. The establishment of the Nyasa Flotilla was possible by the organization of complex logistical operations to transport a total of 12 patrol and landing craft from the coastal port of Nacala to Lake Nyasa, in a route of about 750 km by land. In the scope of the cooperation with the neighbor Malawi, the Portuguese Navy was deeply involved in the organization of its naval forces, transferring to them some of the Nyassa Flotilla boats. The Navy also focused in the resupply of the Portuguese Forces operating in Northern Mozambique, connecting them, by sea, with the main logistical centers in Lourenço Marques and Beira. With the beginning of the construction of the Cahora Bassa Dam and the spread of the FRELIMO guerrillas to the Tete region, in the