In the early years of the 20th century, James Reese Europe was probably the leading African American figure in popular music. Reese came to New York at a time when it was difficult for black musicians to get jobs in theaters and dance halls. He helped organize the first African American musician's hiring hall in Harlem, and led a major fund-raising concert that gave the group its first publicity. Soon after, he connected with Vernon and Irene Castle, providing them with music for their dance shows.
The Castles were among the first superstars of 20th century entertainment, teaching the New York social set - and the rest of the country - to do the new social partner dances that were sweeping the nation. Irene has been called the first modern woman, and Vernon showed that a man who spent his time dancing - rather than sticeng to the business of making money around the clock at the office - could be a respected figure. Irene said that Europe had taught them with Foxtrot (which they then 'cleaned up' for genteel society), and the association with the Castles made Europe the black bandleader of the era.
Europe enlisted in the army during WWI, and was asked to form a band for his regiment. The band, known as the 'Hellfighters' due to their regimental name, became the favorite of General Pershing, and played to the acclaim of French audiences.
On his return from France (I almost wrote Europe), Europe and the band began a tour to take advantage of the publicity they had been accorded. The Boston Globe article that reports the crime states that the Mechanics's Building show was his first in Boston. I have a book that says they played at the Boston Opera House first, and moved to the Mechanic's Building for its larger hall.