This chapter provides an understanding of strategy and the different levels at which it operates. It focuses on the troubled relationship between war and politics; the multidimensional nature of strategy; the polymorphous character of war; the nature of war; and friction. Defence is the most basic and important function of military power. Providing physical security for the nation-state is an essential enabler for the proper functioning of society. Strategy is concerned with the dynamic relationships among ends, ways, and means, whereby ends refers to the policy objectives sought and ways refers to the strategic application of military means in the pursuit of those ends. The performance of Nazi Germany in the Second World War provides a vivid example of what can occur when the levels of strategy are out of kilter. The practice of strategy can also be compromised by the cultural mismatch between the military world and the political world.