YESTERDAY six American servicemen were killed in Iraq, bringing the total since the beginning of the invasion in March 2003 to a least 2'978, five more than the number of people who lost their lives in the 9/11 attacks. Last Saturday on this page, From Our Files included an item that on that day in 1963 US Defense Secretary Robert McNamara had returned from a visit to Vietnam with a recommendation to President Johnson that the American presence there should be increased rather than reduced, as the President had wanted; eventually 400'000 US servicemen took part in the Vietnam operations which lasted until 1973. Perhaps there is no real connection between the loss of life on 9/11 and the death toll of US servicemen in Iraq, but the figures seem to merge to make a point. On the other hand, the recent visit to Iraq of Robert Gates, Donald Rumsfeld's successor as Secretary of Defense, relates directly to Robert McNamara's visit to Vietnam and the tragic misjudgement he made in his recommendation to President Johnson. Will Mr Gates similarly recommend a strengthening of the US presence in Iraq? Unlike President Johnson, George W Bush would probably welcome such advice. Robert McNamara came to recognise the error he made and left the US government. In 1995 he set down the 11 lessons that America should have learned from Vietnam. If anyone in Washington or London had studied those lessons the Iraq war would not have been started.