The Confederate-flag-waving white supremacist who murdered nine African-Americans in a Charleston, S.C., church two years ago made it impossible to evade the fact that the banner — and Confederate ideology generally — had been a rallying point for white supremacy and racial terrorism for more than 100 years.

That tragedy brought fresh urgency to a reappraisal of public monuments that was underway in many Southern communities, including New Orleans, whose mayor announced within days of the massacre that he planned to relocate four Confederate memorials that were built to celebrate a time when black citizens were not fully human in the eyes of the state.

The city plans to place the memorials in storage until an appropriate setting can be found, perhaps a museum that could put them in historical context. But the unfolding backlash — including threats against crane operators and demonstrations — shows the extent to which many citizens are hesitant to part with even the most abhorrent artifacts of history and how little many of them know about when and why these memorials were built.

The first memorial was relocated last month by workers who wore masks and bulletproof vests because they feared for their lives. It is called the Battle of Liberty Place Monument and was erected in 1891 to commemorate the uprising of the Crescent City White League, white supremacists who opposed Reconstruction and the integrated police force that resulted. Decades later, in 1932, a plaque was added expressly articulating its white supremacist origins.