He then returned on Pisa, as adjutant to the divisional commander, and then served in the same capacity on battleships Vittorio Emanuele and Sardegna, being awarded a Bronze Medal of Military Valor for an action in the northern Adriatic in September 1917.

Having been promoted to vice admiral, he was briefly appointed adjunct Deputy Chief of Staff at Supermarina and then commander of the 5th Naval Division in 1943.

In early September 1943, a few days before the proclamation of the Armistice of Cassibile, he was given command of the Naval Department of the Northern Adriatic, with headquarters in Venice, replacing Admiral Ferdinando of Savoy-Genova.

[1][2][3][4][5][6][7] The proclamation of the Armistice on 8 September found him in Venice, where his forces were quickly surrounded by German troops, whose commanders threatened to bomb the ancient city and carry out reprisals on captured Italian personnel if he did not surrender.

After lengthy talks, Brenta surrendered Venice and its garrison of 16,000 men on 11 September, and was then taken as a prisoner of war to Oflag 64/Z in Schokken, Poland, where he remained until late January 1945 (except for a period of imprisonment in Stalag XX-A in Toruń, as punishment for being one of the most vocal anti-Germans among the Schokken prisoners), when he was freed by the advancing Red Army.