‘Clausewitz in his time’ reveals the influences on Clausewitz's thinking and puts the writing of On War in context. Clausewitz served in the Prussian army from age twelve under renowned generals such as Scharnhorst. He entered into the Enlightenment spirit of scientific enquiry, attempting to integrate campaign strategy and battlefield tactics in a unified theory. Experience of Prussia's defeat by the French in the Napoleonic Wars convinced him of the need for political transformation in order to prevail in this new type of war, something he strove to reconcile with his loyalty to the monarchy. In his writings he wanted to systematize all elements of war.