She is best known for opening the Washington Conservatory of Music and School of Expression in 1903 in Washington, D.C.[2] Born in Victoria, British Columbia, Harriet Aletha Gibbs was the daughter of Mifflin Wistar Gibbs, a lawyer in Little Rock, Arkansas, who became the first African-American city judge in the United States, and the former Maria Ann Alexander, a school teacher and graduate of Oberlin College.

Her father, along with hundreds of others, left California during the Gold Rush because of the race badges they were forced to wear and he decided to move to Victoria where he raised his daughters with his wife, Maria.

[9] In 1889, Gibbs became the first African-American woman to graduate from Oberlin Conservatory with a Bachelor of Music degree in piano performance.

[15] She offered recitals in January 1902 which garnered some praise even from far away,[16] as well as being received at the Bethel Literary and Historical Society,[17] a prominent African-American institution of DC.

[25] That Fall Gibbs was noted as director of the music among the colored schools of DC as well as president of the Conservatory – and in September Gibbs and friends took a trip to Europe – London, Paris and the countryside of France – joined by her sister, Ida Hunt, noted as the wife of the US consul to Madagascar.

[27] Newly married in Spring 1906, Gibbs wed Napoleon Bonaparte Marshall, a graduate of Harvard University (A.B.

[33] Newspaper coverage in and beyond DC of the new year noted its history to 1903, that it now had more than 600 students since its founding, and reviewed the faculty in some depth – including staff that would later be officers of the institution as well as her husband.

[38] Marshall also took a trip around promoting the school including to Saint Louis, Missouri,[39] and coverage appeared in The Pittsburgh Courier underscoring its students came from all races and sexes and was called unique for doing so and had now had some 1400 students to date coming from many states though only 23 had stayed on through graduating with a diploma.

[46] Coverage that winter noted a trip to New York and according to The Broad Ax that Marshall was then president of the National Association of Musical and Art Clubs.

[51] That winter Marshall again vacationed in New York,[52] and the Conservancy produced Gilbert and Sullivan's The Mikado in the Howard Theater.

[57] In August 1916 Marshall produced a program on "Negro Folk Songs" at Langston Highschool in Hot Springs, Arkansas.

[59] In 1919 Marshall signed a letter of Baháʼís hoping that ʻAbdu'l-Bahá, then head of the religion, could come back to the West,[60] (recalling the 1910–1913 trips.)

[61] In April 1921 the Conservancy produced a program for a fundraiser that covered periods of "negro music and drama" in New York.

[66] Marshall was approaching having something for a national conservancy set up in New York by May 1924,[67] but instead she went to Haiti with her husband's work, making a brief return trip in August.

[69] During their time in Haiti, the Marshalls were excluded from participation in social activities with other U.S. military officers because of racial segregation.

[69] In 1930 Marshall published The Story of Haiti: from the discovery of the island by Christopher Columbus to the present day.