According to legend, French settlers recognized the "sea of red sedge" between the bluffs to the north and west of the area.

[3] On February 3, 1865, near the end of the American Civil War, two squadrons of the Illinois cavalry attacked Mer Rouge and, according to historian John D. Winters, seized some horses and mules, while also freeing some enslaved African-Americans.

They then "burned about 300,000 bushels of corn [and] some cotton", thus undermining the production power of the pro-slavery rebels.

[4] In August 1922, in a case that would attract national attention, members of the Ku Klux Klan abducted two Mer Rouge men—Filmore Watt Daniel and Thomas Fletcher Richard—on the Bastrop highway.

Following the killings, Louisiana Governor John M. Parker sought help from the U.S. Department of Justice in suppressing Klan violence within the state.

The above-mentioned Red Hill rises 50 feet (15 m) above the plain on which Mer Rouge sits, about halfway between the village and Bastrop.