Petya, the youngest Rostov, is the most impressionable in his attitude about war. He’s grown up hearing about the drama of war, his brother has served, and now he’s just heard an emotive appeal from the Emperor. The crush of people at the Kremlin matches Petya’s mood. The masses are irrational, nearly killing those in their path. Tolstoy suggests this is what war, being irrational, stirs up in otherwise rational people.