Today it may be difficult to understand why the tank idea found such resistance from the leadership of several armies. Part of the explanation is that the entire automotive industry was in its infancy. Tanks were rightly considered unreliable, troublesome equipment as late as the early 1930s. Weak engines, poor transmissions, and fragile, short-life tracks contributed to this reputation. The otherwise-incomprehensible resistance to tanks from 'traditional' military leadership can be partly understood in this light; a tank battalion that loses most of its vehicles due to mechanical failure on a 50-mile movement is not a reliable asset in combat. The international success of the Vickers Six-Ton tank is due more to its high reliability than any brilliance in the design. However, as the decade passed, engines, transmissions and tracks all improved. By the beginning of World War II, reliable engines and transmissions, as well as high-speed suspension designs were all available.