 Complete the following phrase:  In February 1937, following many murders of Italian and Eritrean soldiers and an assassination attempt on Italian East Africas Viceroy, Marshal Rodolfo Graziani, Italian soldiers raided the famous Ethiopian monastery Debre Libanos. The plotters of the assassination had taken refuge at the monastery of the Italian troops and executed the monks and nuns. Afterwards, Italian soldiers destroyed native settlements in Addis Ababa, which resulted -according to Ethiopian estimates- in nearly 30,000 Ethiopians being killed and their homes left burned to the ground. The massacre has come to be known as 