European Travel Time to Moscow

This month exactly two hundred years ago, Tsar Alexander I rode victoriously into Paris to defeat and banish Napoleon. This was payback for Napoleon's visit to Moscow two years before, when 75% of Moscow was burned.

The point is that the plain between Paris and Moscow is easily traveled by cavalry and horse-drawn artillery, and more easily traveled by armored cavalry with close air support. The ultimate defense when Hitler made this trip was shire distance. Hitler started in June and was in the outskirts of Moscow when "General Winter," Russia's traditional ally blunted the Nazi advance. 

Hitler's June 22 attack was delayed six weeks from its original schedule by a British Intelligence fomented insurrection in Yugoslavia. Without that delay, world history may well have been difference, nicht wahr?
With the breakup of the Soviet Union, and many of the new countries allying with Europe, Moscow now is only a couple hundred miles from potential enemy borders. This makes Russia a bit nervous.

An old translation for "Ukraine" is "Buffer."