In which year did the first of the horrific 'New Orleans massacres' take place?

The New Orleans Massacre of 1866 occurred on July 30, during a violent conflict as white Democrats including police and firemen attacked Republicans, most of them African American, parading outside the Mechanics Institute in New Orleans. It was the site of a reconvened Louisiana Constitutional Convention. The Republicans in Louisiana had called for the Convention, as they were angered by the legislature's enactment of the Black Codes and its refusal to give black men the vote. Democrats considered the reconvened convention to be illegal and were suspicious of Republican attempts to increase their political power in the state. The riot "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."

There were a total of 150 black casualties, including 44 killed. In addition, three white Republicans were killed, as was one white protester.