Carl Rochling's painting of the storming of the breach by Prussian Guards during the Battle of Leuthen 

An Italian psychotherapist friend finds my fascination with battlefields unhealthy. Visiting places where men have used the utmost cunning and brutality to kill each other appears to her morbid. Perhaps she is right. But let me try to explain what draws me to these killing fields.

At heart, it is because here pretence is stripped away in the fight for survival. Stendhal, who accompanied Napoleon on his campaigns, wrote that the two qualities men cannot fake are courage and wit. You either have them or you don't. On the battlefield the stakes, life or death, could not be higher. Courage, both physical and mental, is starkly exposed. And the same goes for cowardice.

On this basic attraction other layers rest. There is the genius of great commanders who, in the words of Carl von Clausewitz, author of On War, combine strength of character with "a sense of unity and a power of judgment raised to a marvellous pitch of vision". Then there is the fate of nations on which their decisions depend, the wider political dimension of which war forms an integral part, what Clausewitz famously calls "a continuation of political intercourse, carried on by other means".

Because of its existential nature, armed conflict is a constant spur to technological advance — from bow to musket, machine-gun and missile — whose effects have radically changed the face of the battlefield, and the tactics needed to dominate it. Compare, say, the limited manoeuvring at Crécy in 1346 to the huge deployment at Kursk nearly 600 years later. Sites of battles thus offer great topographical variety.

The history of particular regiments is another draw — the shared experiences which have formed their esprit de corps, the campaigns in which they have fought and, especially in the 18th and 19th centuries, their distinctive uniforms.

Finally, there is the challenge of exploring the battlefield itself. Sometimes, as at Waterloo, it is well mapped and retains enough of its original features to make it easy to read. More often than not, it has been degraded by later development or simply neglected. For such sites you require a detailed history of the encounter, large-scale modern maps, enthusiasm and plenty of imagination.

Armed with Christopher Duffy's Prussia's Glory (Emperor's Press, 2003) and several 1:50,000 maps, I set off with my brother and nephew last autumn to learn more about the most famous victories of one of Clausewitz's heroes — "Old Fritz" or Frederick the Great. Rossbach and Leuthen, fought within a month of each other in 1757, are 220 miles apart as the crow flies, the first near Leipzig in eastern Germany, the second outside Wrocław in south-west Poland. So we based ourselves between them in Dresden.