During World War II the Italian city of Bologna, the regional capital and largest city of Emilia-Romagna, suffered nearly a hundred air raids by the Royal Air Force and the USAAF, mostly aimed at disabling its strategically important marshalling yards, used for the movements of German troops and supplies between Northeastern Italy and central Italy.

In the summer of 1943 the marshalling yards of Bologna, among the largest in Northern Italy, had been included by British commands in a list of railway objectives that would have been useful to attack in order to hamper the movements of German troops and supplies from the Brenner to Rome and from Udine to Florence, as well as on other secondary lines.

The first air raid on Bologna therefore only took place in the night between 15 and 16 July 1943, less than two months before the Armistice of Cassibile, when a dozen of Avro Lancaster bombers, having taken off from air bases in the Lincolnshire and participating in a shuttle bombing experiment (from England to Algeria and return, after refuelling in North Africa), dropped 19 tons of bombs on the city's power plant, hitting it but causing little damage (thus failing the main objective of this raid, the interruption of the supply of electrical power to the railway).

[2][3][4] The second air raid on Bologna, on 24 July 1943, was far heavier; 51 Boeing B-17 Flying Fortress bombers of the 12th Air Force, having taken off from Algeria with additional fuel tanks, dropped 136 tons of bombs on the city's marshalling yards, but many of the bombs also fell on the city itself, destroying completely 85 buildings, destroying partially another 61 and causing damage to a further 259.

[5][6][7][8][9][10] The proclamation of the Armistice (8 September 1943) did not change the situation; Bologna was swiftly occupied by German troops, which kept using its marshalling yards for their movements, and thus the city continued being an objective for the Allied air forces.

295 buildings were completely destroyed, 199 partially destroyed and 371 damaged; due to delay in issuing the air raid alarm (the Italian sighting network had ceased to exist with the German occupation, and the Germans had not yet set up a new network) the population was caught off guard, and this, along with the crowding caused by the market day and by the return of many evacuees who had believed that the Armistice meant that the Allied air raids had ended, resulted in a heavy death toll: between 936 and 1,033 people were killed, over a thousand were wounded.

[11][12][13][14][15][16][17][18][19][20] A further two raids took place in late 1943; on 1 October, three or four bombers of the 12th Air Force, having failed to reach their primary objective at Wiener Neustadt, attacked the marshalling yard of Bologna, but their bombs fell on the city, causing some damage and ten casualties.

[41][42][43] On 1 September 75 RAF bombers dropped 160 tons of bombs on the marshalling yard, hitting both the target and the city, especially the Arcoveggio and Bolognina districts.

They dropped 1,294 tons of bombs (the heaviest bomb tonnage dropped on an Italian city in a single raid during the entire war) on fuel and ammunition dumps, depots and German troop concentrations located in various places in the city, as well as on the Ducati plant – now engaged in munitions production, it was completely knocked out by this raid –, on the Borgo Panigale airfield and on the bridges on the Reno.

The purpose of this raid was to weaken German forces in Bologna and its surroundings in order to support the advance by the Fifth Army, aimed at capturing the city before Christmas.

[57] The dwindling intensity of air raids on the city, along with the movement of the frontline, with the Gothic Line turning the Bolognese Apennine into a battlefield, reversed the evacuee situation; most of the people that had left Bologna during the previous months returned to the city (whose historic centre had been declared "Sperrzone", area where military traffic was interdicted, by the German command), and along with them came tens of thousands of inhabitants of the Apennine villages, fleeing the fighting that was now ravaging their valleys.

[60] In order to house the refugees and the homeless, the Municipal Assistance Authority requisitioned 11,450 apartments and built collective accommodation for 60,000 people, but these measures weren't enough; many camped amid the ruins of destroyed buildings.

[65][66][67] Bologna suffered the highest death toll of any Northern Italian city from air raids: 2,481 civilians were killed, 2,074 were wounded.

Some areas were completely razed, such as the one surrounding Porta Lame, where the medieval gate is today the only pre-war building left standing.

[79] After the war and until the early 1950s, many homeless lived in slums built in various parts of the city, amid the ruins of the Teatro del Corso, in the former Littoriale Stadium, below the portici of San Luca, and in schools and monasteries.