THE Defense Department that Robert McNamara took over in 1961 was already inching, however painfully, toward internal unity. The new Secretary substituted revolution for evolution to create an entirely new order and installed it so firmly that its main lines will most likely prove irreversible.
His principal instrument was the defense budget, which had traditionally been sliced up among the three services, with each recipient determining pretty much how its portion should be spent. McNamara replaced this with a system of allocation by function, or mission, regardless of service bureaucracy. Nine broad missions...