Over the 18th and 19th century, war underwent drastic changes from the scale of conflict to the weapons of war itself. With every new conflict between 1845 and 1991 victory could never be achieved in exactly the same manner and so leadership played a vital role in determining a victory for opposing forces: on the battlefield, through organising the military and increasingly political involvement. The major influences on the constant features of warfare; economies, technology, leadership, tactics and strategy, public opinion, logistics and composition of the military were all affected by the varying conflicts during 1845 to 1991, with some proving more significant as time progressed. This era of warfare can be periodised into interstate industrial warfare, 1845-1945 and the Nuclear age from 1945 onwards. The nuclear age is classed as separate due to its radicalisation of warfare in determining how victory was achieved and what now constituted as a victory as well as the shift in leadership to those in political power.Political leadership and the governmental role in warfare has increased since 1845 and always been at the heart of conflict if one adheres to Clausewitizian ideologies that ‘war is political instrument’ and thus just an extension of a countries aims, ‘an instrument of policy’. Therefore victory was defined and strategy developed depending upon a forces’ political policy which was often led by key political figures of. The German unification wars 1864-1871 were as of a result of Bismarck’s ambition to unite Germany in order to do this land was to be gained from Denmark, Austria and France. Political leadership became more of a focal point with the dawn of interstate industrial warfare due to the creation of mass peacetime armies, (by 1913 the Russian army had grown from 1.2 million to 1.7 million).  The resources needed to sustain their size required a whole nations’ effort and so the Clausewitz trinity of the people, military and the state needed to be maintained by those with political power to assure the war effort was sustained.Total war accentuated the need for political leadership as warfare progressed to the First World War as rationing, conscription and propaganda to reinforce support for war had to be managed by a countries governing body. The Great Patriotic War in Soviet Russia was an extensive tool in rallying the Russian public opinion against the invading Nazis’ through protection of the ‘Motherland’ constantly publicised by the Communist Party in the likes of Pravda. A more attentive population was created because of industrialisation and mass media consequently putting more pressure on how the state conducted a war. This was the case in Russia as apathy of war assisted in the downfall of Tsar Nicholas II. The introduction and increase in colour TV had a very strong impact on American public opinion of Vietnam and therefore forced pressure on government policy, as Robin Day said, “blood looks very red on a colour television.” Post 1945 armed forces fielded by states became more redundant due to increased dependence on modern technology, specifically the destructive capability of nuclear weapons. As a result leadership on the battlefield and militarily can be judged as less important in determining victory as countries turned to Clemenceau’s dictum that war was too serious a business to be left to generals with new eyes. This was due to fear of escalation in a conflict to the point of ‘Mutually Assured Destruction’ (MAD).  Due to the chance of MAD, victory in warfare was harder to define and achieve as destruction of an enemy would also mean destruction of oneself. Therefore the focus was put on the role of diplomacy, political leadership and for countries possessing nuclear weapons; the traditional chain of command was switched to the Head of State. The clearest examples are present in the Cold War through the creation of the Warsaw pact and the Cuban Missile Crisis, in which a ‘Hot Line’ was established between Soviet Russia and the USA: Kennedy and Khrushchev. Military leadership, in the age of interstate industrial warfare, was vital for the planning of warfare due to the ever increasing scale in not only armies but the geographical distance war was spread over. This was closely linked to leadership on the battlefield where victories were achieved through the usage of NCOs, thus training from leaders was important. The Haldane reforms helped to professionalise the BEF  and the rigorous training of the German army earned them the position of the, ‘greatest fighting force of the Second World War’, according to Max Hastings. The Franco-Prussian war required great military leadership from Moltke to mobilise his force of 250,000 using 5 separate railways over 300 miles.This war also highlighted how success was achieved through the creation of the Prussian General Staff. Control was taken from the battlefield commanders and given to the General Staff headquarters; the advantage being the headquarters gave the army greater co-ordination and flexibility. With Moltke in charge it was realised that frontal attack in warfare was over if victory was to be achieved.  This still applied to warfare up to 1991 but didn’t always translate due to military leadership drawing the wrong assumptions. European commanders thought Moltke’s success was gained through powerful frontal attack on the battlefield, later used in World War I.Although military leadership became less important after 1945, there was still a need for it with the ‘advent of high technology. Following the Second World War, competition grew between superpowers, much like the arms race in the escalation to World War I, to build new generations of aircraft, ships, missiles and land fighting machines, each more powerful and more expensive. These new advancements would still require command when used in conflict even the arrival of military technology like guided missiles which helped reduce the military force used. For all the necessities of leadership there are other features which contribute to victory in warfare. Churchill, often seen as a vital part of Britain’s war effort headed some monumental mistakes, the Gallipoli campaign of 1915 and the invasion of Norway 1940 both resulting in little gain and mass casualties.  Hitler’s dictatorial rule dominated military and political responsibility, the disadvantage being that when his generals realised Germany needed to resort a flexible defence, Hitler simply overruled them demanding no retreats, resulting in the hopeless efforts of the 6th army at Stalingrad.  The effect of democracy on leadership is the opposite as the consensus of a nation’s population is more determining thus decisions on how to achieve victory are influenced by electoral consequences. This was particularly the case in the Vietnam War when Nixon won the 1969 election promising he would end the war.