New Orleans and the state government prepared to go to war over control of the city in the summer of 1934. At 10 o'clock one Monday night that July, as Sen. Huey Long sat in his suite atop the Roosevelt Hotel, National Guardsmen under his control broke down the doors of the registrar of voters office across Lafayette Square from City Hall. The heavily armed forces searched and surrounded the building. Snipers trained their guns on the office of Mayor T. Semmes Walmsley, a former political ally of Long who was now his bitter adversary. A tense standoff ensued. Long,...