The New Orleans Massacre of 1866 occurred on July 30, when a peaceful demonstration of mostly black Freedmen was set upon by a mob of white rioters, many of whom had been soldiers of the recently defeated Confederate States of America, leading to a full-scale massacre. The violence erupted outside the Mechanics Institute, site of a reconvened Louisiana Constitutional Convention. The Republican Party of Louisiana had called for the Convention, as they were angered by the legislature's enactment of the Black Codes and refusal to extend voting rights to black men. White Democrats considered the reconvened convention to be illegal and were hostile towards Republican attempts to gain increased political power in the state. The massacre "stemmed from deeply rooted political, social, and economic causes," and took place in part because of the battle "between two opposing factions for power and office." According to the official report, a total of 38 were killed and 146 wounded, of whom 34 dead and 119 wounded were black. Unofficial estimates were higher. Gilles Vandal estimated 40 to 50 blacks were killed and more than 150 wounded. Others have claimed nearly 200 were killed. In addition, three white convention attendees were killed, as was one white protester.During much of the American Civil War, New Orleans had been occupied and under martial law imposed by the Union. On May 12, 1866, Mayor John T. Monroe, a Democrat who had ardently supported the Confederacy, was reinstated as acting mayor, the position he held before the war. Judge R. K. Howell was elected as chairman of the convention, with the goal of increasing participation by voters likely to vote for removal of the Black Codes.The massacre expressed conflicts deeply rooted in the social structure of Louisiana. It was a continuation of the war: more than half of the whites were Confederate veterans and nearly half of the blacks were veterans of the Union army. The national reaction of outrage at the earlier Memphis riots of 1866 and the New Orleans Massacre helped the Radical Republicans win a majority in both houses of Congress in the 1866 midterm elections. The riots catalyzed support for the Fourteenth Amendment, extending suffrage and full citizenship to freedmen, and the Reconstruction Act, to establish military districts for the national government to oversee areas of the South and work to change their social arrangements.