In late June 1936, during the Italian conquest of western Ethiopia following the occupation of Addis Ababa, the Italian colonial government under Viceroy Rodolfo Graziani organized an air expedition to Lechemti (Nekemte) to secure the submission of Oromo leader Dejazmatch Hapte Mariam and establish an Italian garrison. The mission, led by General Vincenzo Magliocco, departed Addis Ababa on 26 June 1936 aboard two Caproni Ca.133 bombers and one IMAM Ro.37 reconnaissance aircraft, carrying 3,000 silver Maria Theresa thalers intended to fund a local force. The party landed at the Bonàia airfield near Lechemti around 13:00, where they were met by Oromo delegates sent by Hapte Mariam, and set up camp for the night, believing themselves protected.
According to the account, roughly 150 students from the Holeta military school, previously trained by Swedish officers and sent to Lechemti by the provisional Ethiopian government in Gore, had arrived in the area to monitor Hapte Mariam. On the night of 26–27 June 1936, these students, acting outside Hapte Mariam's control, attacked the Italian camp. The Oromo guards assigned to protect the expedition reportedly fled at the outset of the attack. Eleven of the twelve Italians in the camp were killed, including General Magliocco and Major Antonio Locatelli, a decorated aviator. The three aircraft were burned. The sole survivor was Father Mario Borello, a Consolata missionary who had earlier facilitated contact with Hapte Mariam and who witnessed events from a nearby grove; his testimony remains the only detailed account of the attack, and later writers, including Angelo Del Boca, have noted inconsistencies in his reported movements.
News of the deaths caused public mourning in Italy. Benito Mussolini sent a telegram to Locatelli's family calling him "one of the purest and most intrepid souls of Fascism." Foreign Minister Galeazzo Ciano proposed an aerial retaliation against Lechemti, though large-scale retaliation was deferred after the League of Nations lifted sanctions on Italy on 4 July 1936. Sources indicate that on 5 July 1936 Italian aircraft bombed a Swedish missionary school complex, and Italian press reported "mass reprisal actions" against villages believed to have sheltered the attackers.
In the following months, Father Borello persuaded Hapte Mariam to submit to Italian rule; on 8 October 1936 Hapte Mariam swore allegiance to Italy at Lechemti. All twelve members of the original expedition were later awarded the Gold Medal of Military Valor. A memorial to the dead was inaugurated at Bonàia in February 1939 by Viceroy Amedeo d'Aosta and Colonial Minister Attilio Teruzzi; the remains of the dead had been recovered by Father Borello in December 1936 and interred there. The memorial and aircraft wreckage were later destroyed following the defeat of Italian forces in East Africa and the restoration of Haile Selassie.