The Canberra is also suprisingly quiet in flight. The Viet Cong wouldn't have known what hit them
During the Rhodesian war in the 1970s Canberras were used against terrorist bases in Zambia and Mozambique. Monkeys (with superior hearing to humans) at these bases which had previously experienced a bombing raid would become very agitated at the sound of Canberra engines and could be relied on to give a few extra seconds of warning before the bombs came raining down.
The Rhodesian Air Force developed a method of starting the Canberra engines using compressed air which gave considerable cost savings over the cartridges.