Shards of Honor by Lois McMaster Bujold
Leadership is mostly a power over imagination, and never more so than in combat. The bravest man alone can only be an armed lunatic. The real strength lies in the ability to get others to do your work.
A Caligula, or a Yuri Vorbarra, can rule a long time, while the best men hesitate to do what is necessary to stop him, and the worst ones take advantage.
"So what does the man have, anyway?" "I don’t know. The virtues of his vices, perhaps. Courage. Strength. Energy. He could run me into the ground any day. He has power over people. Not leadership, exactly, although there’s that too. They either worship him or hate his guts. The strangest man I ever met did both at the same time. But nobody falls asleep when he’s around." "And which category do you fall in, Cordelia?" asked her mother, bemused. "Well, I don’t hate him. Can’t say as I worship him, either." She paused a long time, and looked up to meet her mother’s eyes square on. "But when he’s cut, I bleed."