* Apr 10, 1868 New Orleans La.
† Aug 25, 1946 New Orleans La.

As a brass band musician he played with: Excelsior, Onward Brass Band

Born as John Baptiste Delisle, son of Antoine Joseph & Rosine DeLisle, married Mary (Mamie) Wells on May 24, 1894.
Zue Robertson was Baptiste Delisle's cousin.

The name Delisle was very common during that time. It was also spelled Delille or Delile but all references to Baptiste have it spelled Delisle. I have also seen his first name as John or Jean (French pronunciation) as well as Baptist and Baptiste. Most of the time, he used J. Baptiste Delisle or Baptiste Delisle. His father Antoine J. Delisle (a free man of color, and civil war veteran) used all three spellings. This makes it all so interesting and challenging to research.

I have attached a copy of his funeral bill and a pension letter which my grandmother kept and a copy of his music sheet I received from the Tulane archives. Thought you might enjoy seeing them.

Funeral Bill                                               Sheet music with probably the signature of Delisle


Pension letter

Source: Dianne Barker, who's working on her family history.

Around 1890 he joined the Onward Brass band and John Robichaux in 1894. He and entire unit of members of the Onward Brass Band enlisted for Spanish-American War. He rejoined Robichaux in 1905 after long illness.16

A recruiting officer visited the Onward Brass Band during a Wednesday evening concert in July, 1898. Most of the members enlisted in the Army. The band, under the direction of James MacNeil, which became known as The Ninth Immunes Regimental Band, was sent to Cuba. On their return to the U.S.A. in 1899, they marched down new York's Fifth Avenue in one of the great Victory Parades. Source: Jazz New Orleans, Samuel Charters.

Baptiste Delisle suffered a nervous breakdown a few months after returning from Cuba and was institutionalized for five years. His place in the Onward Brass Band was taken by Buddy Johnson.2

Bud Scott mentioned that Baptiste was in John Robichaux's band in 1904, when he joined them.
It's said that Baptiste was the uncle of Albert T. Baptiste, a violin player and leader of the Silver Leaf Orchestra. Pops  Foster speaks about Baptiste as "one of the best trombone players we had in New Orleans. Pops Foster also mentioned that Baptiste and George Williams were the first to switch from valve to slide trombone.

Wellman Braud mentioned in an interview that Baptiste Delisle gave Zue Robertson some lessons. He also mentioned that Baptiste played in Buddy Bolden's band.3

As we see on the sheet music John Baptiste spelled his name as DeLisle.

He was believed to have been one of the first valve trombonenists to convert to slide trombone.18
 
Sources (internet):

Sources (brassband history):
2 Fallen Heroes by Richard H. Knowles
3 New Orleans Style by Bill Russell
16 New Orleans Jazz, family album by Al Rose and Edmond Souchon
18 Exploring Early Jazz by Daniel Hardie
Diana Barker