''I beat the Russians every time,'' said Napoleon, ''but that doesn't get me anywhere.''Armand de Caulaincourt was one of the highest officials in the French Empire, constantly riding at Napoleon's side. His memoirs are hailed as the most accurate and best written eyewitness account of Napoleon's disastrous attempt to conquer Russia. The cycle of Napoleonic conquests ended in Russia's winter of ice and snow. Nowhere is that awful event described as vividly as in these memoirs. Napoleon entered Russia triumphantly on June 18, 1812, with over 500,000 men, while the remnants that staggered back out were merely a few ragged thousand. It was the greatest military disaster in history.With an introduction by Dr. Jacques-Olivier Boudon, president of the Institut Napoleon, University of Paris IV-Sorbonne.