Napoleon maintained strict, efficient work habits, prioritizing what needed to be done. He cheated at cards, but repaid the losses; he had to win at everything he attempted. He kept relays of staff and secretaries at work. Unlike many generals, Napoleon did not examine history to ask what Hannibal or Alexander or anyone else did in a similar situation. Critics said he won many battles simply because of luck; Napoleon responded, "Give me lucky generals," aware that "luck" comes to leaders who recognize opportunity, and seize it. Dwyer argues that Napoleon's victories at Austerlitz and Jena in 1805-06 heightened his sense of self-grandiosity, leaving him even more certain of his destiny and invincibility. By the Russian campaign in 1812, however, Napoleon seems to have lost his verve. With crisis after crisis at hand, he rarely rose to the occasion. Some historians have suggested a physical deterioration, but others note that an impaired Napoleon was still a brilliant general.