World War 1 (1914-18) was a long static trench war in which artillery and machine guns made mobile ground warfare almost impossible, suicidal, for both infantry and Cavalry. The element of fire, from the machine guns and artillery, totally neutralized the element of maneuver, at least for the vulnerable infantry and Cavalry. But during the war, two new revolutionary weapon systems were invented and saw initial combat use, the armored tank, and the combat aircraft. Relative to the infantry and Cavalry, both were almost invulnerable to machine gun and artillery fire. In addition to that, their growth potential as powerful motorized vehicles was about to revolutionize warfare. After the war, various military establishments gave various levels of attention to further study and developing these new powerful weapons, and to the new possibilities of combining their potential with other weapons. In maritime powers the aircraft was integrated with large ships to create the aircraft carrier, which thanks to its much greater strike range totally outclassed the big guns battleships which dominated the seas for centuries. In Russia, with its vast distances, a gigantic force of paratroopers was established to give infantry a whole new mobility, and a huge fleet of light fast tanks was established to give the military new mobility over the vast land. In Britain, well armored "Infantry tanks" were developed to provide the infantry with mobile fire support, and lighter "Cruiser tanks" were developed to replace the obsolete Cavalry.
Other armies, like in France and Poland, remained conservatively stuck in the previous war. France spent its defense budget on building a mighty line of super-trenches, the Maginot line, with huge fortifications, underground bunkers and tunnels, and heavy but totally stationary artillery. The Polish army's main mobile force remained the obsolete Cavalry. Both spent much too little budget and thought on their air forces.
The German military, bound by severe post-war limitations, was practically forced to develop the most efficient new tactics, which naturally involved using tanks and aircraft for mobile ground warfare. It also learned from and improved over the ideas of British military theoreticians, mainly Basil Liddell-Hart, which openly published their new ideas about fast and deep armor advancement as the future combat tactic.
Very early in the 1920s, General von Seeckt, the head of the German military, wrote that the future of warfare will be in operating smaller but highly mobile high quality forces which would be made even more efficient by support from aircraft. In 1929, a German infantry officer, Heinz Guderian, was assigned to the common German-Russian tank school in Kazan, which was established to allow the Germans to bypass the post-war limitations by training in operating tanks in Russia.
Guderian read the British books about the new principles of tank warfare, and while in Britain Liddell-Hart's ideas were given little military attention, Guderian practically developed them over several years and demonstrated them to his superiors in military exercises and war games.
There were two factors which helped Guderian's tactical ideas become dominant in the German military more than in any other military. The 1st factor was that after the defeat in World War 1 there were enough open minds in the German higher ranks ready to examine new ideas. The 2nd factor was that while so many countries conveniently believed in pacifism after the bloodshed of World War 1, Germany's new leader since 1933, Adolf Hitler, intended to go to a major war again, and as soon as possible, and he pushed the German military back in full shape, ignoring the peace treaty's limitations and spending a huge portion of the budget on re-armament.
Hitler needed the right tool for his grand war plans, something that would make his future war very different from World War 1, and will fully exploit the German advantages in military professionalism and industry. Although he was just a Corporal in World War 1, Hitler had good and creative military perception, both tactical and technical, and so when he observed a combined exercise of tanks and motorized infantry led by Guderian shortly after he came to power, he immediately understood that he found his military tool. He said "That's what I need, That's what I want to have". With Hitler's strong support, the tiny German tank and motorized forces began to rapidly expand, and tank development and production was strongly boosted. Guderian himself was rapidly promoted to be the commander of one of the new "Panzer" (armor) divisions, in 1938 he became the commander of the 1st German Panzer Corps, and later that year he became the "Chief of mobile forces", with direct access to Hitler. With his spirit and training, and with large amounts of new modern Blitzkrieg weapons, the German military was getting ready to implement Blitzkrieg in the battle field.