1969: In 1968 and 1969, the United States dropped on South Vietnam one and a half times the tonnage of bombs dropped on Germany by all the Allies during the Second World War.
By 1969, the explosive force of the bombs dropped on North Vietnam each month was equivalent to two atomic bombs.
Up to the end of 1971, the United States had dropped 6.3 million tons of bombs on Indochina – more than three times the amount it dropped in all theatres during the Second World War.
In South Vietnam alone, there were 21 million bomb craters.
Source: Marvin E. Gettleman, Jane Franklin, Marilyn Young and H. Bruce Franklin, Vietnam and America: A Documented History (1985), p. 461