The tank was first developed by the British and French during World War I as a means to break the deadlock on the Western Front. More so than any previous war, the balance of power lay with the defense, as machine guns, trenches, bunkers, barbed wire, and rapid-firing rifles all made frontal assaults on established positions prohibitively costly. In the closing months of the war, the tank partially evened up that balance, even as the war’s commanders initially proved unsure of how to use them. While it cannot be said that the tank won the war, it contributed to its end and if the fighting had continued another year, the mass production that had started in Allied countries may have proved decisive.

World War II was the culmination of a quarter century of tank development, and it would also be the first major test of tanks in mobile warfare during which they had to face other tanks. However, many of the tanks were constructed with the static warfare of the Western Front in mind and were thus slow and had short operational ranges. Others were too light to face opposing tanks or the new generation of anti-tank weapons that hadn’t existed in World War I. The unsuitability of these tank models for this new kind of warfare was quickly recognized, and the belligerent powers scrambled to create better designs. As each new, improved model came off the assembly lines, the opposing powers rushed to create a tank that could beat it. In that regard, World War II was also a war between rival engineers.

The beginning of World War II found the major powers developing tanks to some extent, but lingering ideas from World War I affected the development of tanks during the Interwar period.