'Bona' was an Italian unrealised plan for an attack by two heavy cruisers on Allied shipping off the coast of North Africa (April 1943).
After the Allied 'Torch' landings of November 1942 in the French North-West African possessions of Morocco and Algeria, which spurred the Axis occupation of Tunisia, the weight of naval warfare in the Mediterranean moved decisively to the west. At this juncture German and Italian political pressure forced the Supermarina into the planning of an operation against Allied sea traffic between Bougie and Bône on the eastern end of the Algerian coast.
Since November 1942 the Italian armed trawler Corrispondende Omega, flying the French flag, had been involved in an investigation of Allied naval traffic along the Algerian and Tunisian coasts, and its findings were crucial to the development of the 'Bona' operation, which had been planned to satisfy Italian political rather than military requirements by proving to the Germans that the Italian navy still possessed an offensive determination and capability. However, so short of fuel was the Italian navy that success, in any, could not have been repeated.
The Italian navy’s only active naval force at this time included two heavy cruisers, Gorizia and Trento of Ammiraglio di Divisione Angelo Parona’s 3a Divisione Incrociatori, all other heavy ships having remained in port for several months to save the little oil fuel left and so make this available for a proposed final sortie of the Italian navy’s three modern battleships. Added to this was the fact that since March 1943 the shortage of destroyer escorts had become acute, and the seven surviving 'Poeti' and 'Soldati' class ships were therefore pulled back from certain destruction in the waters off Tunisia. It was then decided that the 3a Divisione Incrociatori would be escorted only by two destroyers and, in the event of a further crisis in Italian naval affairs, could have done without them.
Prerequisites for the launch of 'Bona' were up-to-the-minute aerial reconnaissance and the securing of total surprise in order to avoid direct confrontation with superior Allied forces. Weighing anchor from La Maddalena on the island of Sardinia, the cruisers were then to steam south to reach their assigned area at dawn. After this the plan had two alternative objectives: for the cruiser force to find and destroy any Allied convoy as it approached Bône, and then retire to Italian waters or, in the event that there was no convoy, for the cruiser force to steam at 30 kt within sight of the base used by Allied cruisers, shell the base and any larger warships at anchor, and then return at full speed to Italian waters.
The whole plan was posited on the very unrealistic assumption that the Italian and German air forces could contain any and all Allied air threats to the Italian cruiser force.
During the first months of 1943 Allied air attacks by day against Axis convoys to Tunisia had been undertaken primarily by British squadrons based in Malta and Libya, and had not inflicted decisive losses on ships running to and from Tunisian ports at high speed. Early in April, however, the Italian situation changed entirely for the worse with the arrival of new US bomber units, which introduced the highly effective tactic of carpet bombing from higher altitudes by between 50 and 60 aircraft. The situation at night was quite different, for the British had refined their night attack techniques to attain a high level of expertise which the Italian and German air forces were unable to defeat.
The Italians paid particular attention to the electronic equipment of the ships involved in this mission. First, in addition to the installation of a German 'Metox' radar detector, the service planned to fit the Trento with Tipo E.C.3 Gufo, one of the latest Italian radars, but it was soon realised that the installation would have required too much time. It was decided instead to have the cruisers escorted by the destroyers Legionario and Alfredo Oriani, which were equipped with the German 'DeTe' radar equipment.
Delays resulting from the fine tuning of the equipment, and the need to operate during a night without moonlight, forced the Supermarina to postpone 'Bona' from the middle of March to April.
The time lost was not wasted: the cruisers completed a major gunnery exercise on 18 March in an effort to offset a lack of gunnery proficiency stemming from the fact that the Italian fleet had not undertaken any gunnery training at sea since 19 October 1942.
On 10 April, less than 48 hours before the cruiser force was scheduled to sail, the island of La Maddalena was bombed, for the first time, by the Allied air forces. The raid, undertaken by 136 aircraft including 84 Consolidated B-24 Liberator heavy bombers, was delivered with great accuracy and inflicted grievous harm: Trieste soon sank with her hull completely devastated and the motor torpedo boats MAS-501 and MAS-503 were also sunk, while Gorizia sustained damage severe enough for her captain to beach the ship in shallow water. (Gorizia was later salved and sent for repair to La Spezia, where she was seized by the Germans on 8 September 1943.)
The loss of the only active naval force available led the Italians to make an indefinite postponement of 'Bona'. The Italians also began to look for a possible traitor who might have warned the Allies and thereby occasioned the attack on La Maddalena, but in reality the Allies had suspected such an operation and kept La Maddalena under air surveillance. The gunnery training sortie of 18 March had not escaped the attention of the Allies, which brought forward a bombing raid already being planned and thus pre-empted the Italian effort.