Mistakes in aim cost the lives of several civilians, but the pressure on the governor contributed to the withdrawal of loyalist troops to the outskirts of the city on 8 July.
On the sides of Penha and Ipiranga, the divisional artillery launched intense attacks beginning on 11 July, targeting mainly the working-class neighborhoods in the south and east of the city, such as Brás, Belenzinho and Mooca, where the loyalist troops were trying to advance.
Foreign diplomatic representatives and São Paulo's economic elite, harmed by the chaos in the city, tried to negotiate an interruption in the bombings, but the government did not give in.
[2] The loyalists retreated to the outskirts of the city on 8 July, grouping in the directions of Santos and Rio de Janeiro, with the seat of the state government being transferred to the Guaiaúna railway station, in Penha.
[3] Against 3 to 3,500 rebels, the federal government brought reinforcements from other states, forming a loyalist army of 14–15,000 men, armed with the most modern equipment available in the country, with which the reconquest of the city began.
[9] The army's most powerful artillery pieces were the 155 mm howitzers, 1917 model, by Schneider, whose shots had a range of up to eleven kilometers, and could kill a person within a 600-meter radius from the hit point.
[9] From there, they fired the first artillery shots of the conflict, after 09:00, aimed at the Campos Elíseos Palace, seat of the state government,[34] where the loyalist forces focused their defensive effort.
[36] General Isidoro Dias Lopes suspended the bombardment due to civilian deaths,[39] but it was resumed at 16:00, targeting the region of Praça da Sé, where the government secretariats were located.
The bombardment only ceased when revolutionary commander Miguel Costa was informed of the prisoners held inside the barracks—captains Joaquim and Juarez Távora and lieutenants Índio do Brasil and Castro Afilhado.
[2] Heavy artillery, positioned, depending on the sources, on Morro dos Ingleses, the Araçá Cemetery or on Campo de Marte itself, convinced the governor to leave the place and take refuge in the Secretariat of Justice, next to Patio do Colégio.
[46] In a rare case of friendly fire, on 12 July, 105 mm guns hit rebel positions at the Maria Zélia Factory, whose defenders had requested artillery support.
[48] In the book Sob a metralha, published in 1924, Ciro Costa and Eurico de Góis accused the rebels of having fired at random, with hidden guns, to deceive the population, making them believe that they were being bombed by the government.
[66][67] Around 12 July, the Pantaleão Telles brigade received artillery support in its attack on the Maria Zélia Factory, opening furrows in the ground just five meters from the enemy positions.
[86] When loyalist bombings reached residential areas, terror was widespread;[87] its victims lived with fear, the destruction of homes, and the death of acquaintances and family members.
José Carlos de Macedo Soares, president of the Commercial Association of São Paulo, asked general Isidoro to release the arrested firefighters, and the request was granted.
[32][108] Macedo Soares managed to convince general Abílio de Noronha, former commander of the 2nd Military Region and now a prisoner of the rebels, to mediate peace negotiations.
This is a hard necessity that we urgently need to accept as imperative in order to put an end, once and for all, to the state of affairs created by this sedition that debases our credit as a cultured people.
[32] Juarez Távora defined the bombing as "deadly for the civilian population, but innocuous for the revolutionary troops", "without the precise directive of a prefixed military objective, without careful observations that corrected its errors, without shortage of ammunition that limited it", "dispersive and useless".
[127] General Sócrates' report described how the 155 mm guns were called in to destroy "depots and enemy organizations", presenting loyalist artillery as an instrument to overcome military resistance.
[128] Ciro Costa and Eurico de Góis defended the bombing, claiming the "fatality of this unpatriotic moment"; if there were no orders to spare civilians, the city would be off the map; and only "rare shots" missed their targets.
Having no Reims cathedral to demolish, Sócrates targeted his cannons sometimes at a gleaming new hotel, then a beautiful modern factory, at one of the city's new skyscrapers, wrecking a tram, sending a pastry shop flying, destroying a school, blowing up a square or a bar.
[130][136][61][83] Brazilianist Frank McCann speculated that the Brazilian Army was setting aside advice from the French Military Mission and reverting to the brutal methods it used in the Canudos and Contestado wars, an astonishing decision; the population was instructed to leave the city, but São Paulo was too big to be razed like the villages in these two conflicts.
[61] Cotonifício Crespi, for example, "dominates the entire height of Mooca", in the words of lieutenant João Cabanas, who positioned a machine gun on top of the building.
[153] Brazilians had already been exposed to the subject since the First World War, when, in the words of Abílio de Noronha, "the press, in almost all countries of the Universe, spent tons of ink and the best of its flower of rhetoric to preach hatred against the Germans, calling them pirates and Huns, because they fired their artillery at open cities; the great dailies of our country tuned their pitch to that of the allies and rare was the newspaper that did not launch anathema against those vulgar murderers, destroyers of cities, monuments and temples".
[154] Noronha called São Paulo an "open city par excellence, and occupied by a small number of rebels, without fortifications that required long-distance destructive shots".
[57] Manoel da Costa Manso, a justice of Brazil's Supreme Federal Court (STF) criticized the "inhuman and criminal bombing, dumping cannons on the open city, without respect for the civilian population".
[155] Jurist Lemos Brito defended the government's actions, questioning this interpretation of open cities: "the legitimacy of the aggression does not really depend on the fortification, but on the defense of the place at gunpoint".
According to Brazilian jurist Lafayette Rodrigues Pereira, "if the open city shelters the enemy in its bosom, if it resists by raising barricades and converting houses and buildings, walls and terrain accidents into trenches and redoubts, immunity disappears".
[157] In the case of the bombardment of a city defended by enemy forces, the commander of the attacking troops had the obligation to notify the local authorities in advance, except in circumstances where surprise is permitted.
According to jurist Clóvis Beviláqua, "the bombardment must be directed against the fortifications of the city and its dependencies and not, intentionally, against the part inhabited by the civilian population, in order to move it to influence the garrison, so that it does not persist in the resistance".