In 1890, he was among the founders of the Comité des Citoyens, which fought the 1890 Separate Car Act through legal challenges, leading to the US Supreme Court Case, Plessy vs Ferguson (1896).

The Desdunes family were Saint Dominican Creole refugees who fled from Saint-Domingue (now Haiti) during the 1791 Haitian Revolution,[1] at which time they gained asylum in New Orleans.

Rodolphe and Clementine had at least four children, Mary Celine (March 25, 1879), John Alexander (1881), Louise (1889), and Oscar Alphonse (1892).

Other associates of Mamie included performer Bunk Johnson and promoters Hattie Rogers and Lulu White.

In 1874, under the command of former Confederate General and then adjutant general of the Louisiana Militia James Longstreet, Desdunes was among the injured in the Battle of Liberty Place, fought between the pro-Republican city, state, and federal forces, and a pro-Democratic, largely ex-Confederate group called the White League.

He remained a strong supporter of the rights and honors due to the black veterans of the United States Civil War.

[12] In 1908, as a part of his Customs department duties, Desdunes was supervising the weighing of cargo on a ship when granite dust blew into his eyes, blinding him.

As part of the Compromise of 1877, most of the federal troops were withdrawn from the South, enabling white supremacists to work more freely to suppress black rights.

In 1878, the association, with Desdunes an officer and Thomas J. Boswell as president, were active in condemning lynchings: dozens of blacks had been killed in Louisiana in the 1870s.

[13] In 1884, Rodolphe and his brother, Aristide, as well as Paul Trévigne, Arthur Estèves, and Louis André Martinet, as a part of a group called L'Union Louisiannais, reopened the Couvent School.

Desdunes was a part of the American Citizens' Equal Rights Association of Louisiana in 1890, protesting to the state assembly against legislation that imposed second-class status on blacks.

"[18] Aristide, Rodolphe and Daniel Desdunes, Louis Martinet, Eugene Luscy, Paul Bonseigneur, L. J. Joubert, P. B. S. Pinchback, Caesar Antoine, Homer Plessy and others formed the Comité des Citoyens to organize black civil rights efforts.

[1] Luscy, Bonseignure, Rodolphe Desdunes, Joubert, and Martinet secured Plessy's release on bail that same day.

[1] Messieurs: Sirs, Heros, Vous qui Venez de la France lointaine, You Heroes, you coming from distant France, Vous, defenseurs du droit et de la libert[é]; You defensors of the rule of law and liberty, Des humbles descendants de la race Africaine, You humble descendants of the African race Veuillez bien accueillir l'hommage merit[é] Please receive this well deserved tribute Nous, aussi, nous voulons temoigner a la France, We as well, we want to entrust France Au nom de l'avenir, du present, du pass[é], In the name of the future, the present and the past Nos sinceres souhaits, notre reconnaissance, With our sincere wishes and gratitude, Tel que, de tous les temps, notre ame la pense.

From July through October 1895, Desdunes published translated excerpts from Joseph Saint-Rémy’s five volume work, Pétion et Haïti, for the New Orleans Crusader.

[14] Just before losing his sight, Desdunes finished a book about the contribution of Creoles to Louisiana history, Nos Hommes et Notre Histoire, which was published in Quebec in 1911.

In the book, Desdunes uses personal reminiscences and scholarly biography to explore the lives of remarkable men in letters, fine arts, music, war, peace, and teaching.

The story starts with the role of free black soldiers under General Andrew Jackson in the Battle of New Orleans in the War of 1812 and continues to explore the contribution of creoles to Louisiana and to the United States.