Eight wars figure in A. J. P. Taylor's examination of how wars begin. Six were major wars fought in Europe since the French Revolution; the seventh - the Second World War - was fought all over the world; the eighth - the Cold War - was a major conflict which without leading to actual war had many of its characteristics. What started them ? Some had a long background, others were brought about by the overweening ambitions of a single man, Napoleon at the beginning of the period, Hitler towards the end. Public opinion, secret diplomocy, jingoism, armament manufacturers, even historians have not escaped censure. But often, as Mr Taylor found to his surprise, the actual declaration of a war bears little relation to its profound cause. Wars in fact have sprung more from apprehension than from a lust for conquest. Every Great Power is suspicious of any likely or even unlikely rival. What seems defence to one will always appear as an aggressive preparation to another. `With nuclear weapons the Balance of Power has been replaced by the Balance of Terror,' writes Mr Taylor. 'This only means that the chances are less, not that they have been eliminated. In the old days the deterrent worked nine times out of ten. Now presumably it will work ninety-nine times out of a hundred. But if past experience is any guide, the hundredth occasion will come.'