When Tolstoy wrote his famous battle scenes (Borodino), there were probably many details he took for granted since he could count on his readers being somewhat familiar with how a battle at the time was fought (though by Crimea was was mechanizing).
Here, Massie explains in all the terrible, bloody detail how these battles were really trained, fought, won, and lost. Calvary, bayonet (pike), siege.
Terrifying.