Long before he assembled one of the largest far-right anti-government militia groups in U.S. history, before his Oath Keepers stormed the U.S. Capitol on Jan. 6, 2021, Stewart Rhodes was a promising Yale Law School graduate. He secured a clerkship on the Arizona Supreme Court, in part thanks to his unusual life story: a stint as an Army paratrooper cut short by a training accident, followed by marriage, college and an Ivy League law degree. The clerkship was one more rung up from a hardscrabble beginning. But rather than fitting in, Rhodes came across as angry and aggrieved. He railed...