Bombing of Plaza de Mayo

On 16 June 1955, thirty Argentine Naval Aviation aircraft — 22 North American AT-6s, five Beechcraft AT-11s, and three Consolidated PBY Catalina flying boats — took off from Morón Air Base and bombed and strafed Plaza de Mayo, the main square of Buenos Aires, and the adjacent Casa Rosada, seat of the Argentine government. The attack occurred during official demonstrations organized in support of President Juan Perón, held to condemn an alleged flag-burning incident by his opponents during a recent Corpus Christi procession. It formed the opening phase of an attempted coup d'état against Perón that was ultimately unsuccessful.

The attack began at 12:40 pm on a Thursday during working hours, without warning, striking a crowded city center. Early casualties included passengers of a trolleybus, killed when a bomb struck it directly. Rebel Marine infantry companies attempted to seize the Casa Rosada but were repelled by loyalist Army and Mounted Grenadier forces. As union leaders mobilized workers to defend the government, large crowds gathered near the Casa Rosada and were caught in the open when the main air assault, including Gloster Meteor fighters, struck around 15:00, causing the bulk of civilian casualties. Aerial combat also occurred, with a loyalist Meteor downing a rebel AT-6 over the Río de la Plata.

Fighting ceased at 17:20 local time after the rebel-held Ministry of the Navy surrendered to Army units. Between 9.5 and 13.8 tonnes of ordnance were dropped during the operation. Death toll estimates vary by source: an official police report by commissioner Rafael C. Pugliese dated 22 June 1955 recorded 136 dead, including five police officers, based on hospital and morgue records; Peronist sources at the time claimed around 400 dead; a 1965 magazine account described roughly five hundred dead or seriously injured; and a broader tally cited elsewhere put identified bodies at 308, including six children. In 2023, Argentina's Chamber of Deputies released an updated report stating that 111 trade unionists of the General Confederation of Labour (CGT) were among the dead, along with six minors, one aged three. Combined rebel and loyalist military casualties totaled 44.

Following the failed coup attempt, rebel pilots fled to Uruguay, where several were interned until Perón's eventual overthrow in September 1955 in a separate coup, the Revolución Libertadora. One rebel leader involved in the June bombing, Gargiulo, died by suicide after being informed he would face trial under martial law. That same night, Peronist crowds set fire to eight churches, two basilicas, and the Curia office in retaliation for perceived Catholic Church support of the coup plotters. Bullet and shrapnel marks remained visible on some buildings at the square as of 2023.