Short answers, pulled from the story.
The word strategy emerged from the Greek office of the general, known as strategos, meaning the leader or commander of an army. It originally described the narrow art of arranging troops on a battlefield before evolving into a complex discipline of planning and execution.
Carl von Clausewitz, who lived from 1780 to 1831, declared that war was a continuation of politics by other means. He argued that the purpose of all strategy was to achieve the political goal that the state was seeking to accomplish, making war a real political instrument rather than an end in itself.
Sun Tzu, who lived between 544 and 496 BC, taught that the supreme art of war was to subdue the enemy without fighting. His treatise The Art of War focused on asymmetric warfare and deception rather than direct confrontation.
The Mongol armies utilized a strategy of maneuver and continuous assault that stressed Chinese, Persian, Arab, and Eastern European forces until they collapsed. This approach prioritized speed and psychological pressure over static defense, allowing them to coordinate vast numbers of men across the steppes with unprecedented efficiency.
Technological change had an enormous effect on strategy during the early 20th century, as the use of telegraph and later radio enabled the rapid movement of large numbers of men. One of Germany's key enablers in mobile warfare was the use of radios, which were put into every tank, allowing for a level of coordination that had never been achieved before.
During the Cold War, Soviet strategy was dominated by the desire to prevent, at all costs, the recurrence of an invasion of Russian soil, leading to a policy of no first use which in fact was a posture of launch on warning. The United States and the Soviet Union developed strategies of massive retaliation in the 1950s, flexible reaction in the 1960s, and realistic threat and containment in the 1970s.