Jack 'Boss' Marshall (born May 11, 1893) was a Negro Leagues pitcher and manager for several years before the founding of the first Negro National League, and in its first several seasons.
Marshall was pitching for the (Holden, MO Brown's) Tennessee Rats by 1917 at the age of 24.
He would move on to the Chicago Union Giants traveling team, one of two teams using that name in 1919. During a game in Omaha, Nebraska, Marshall was reportedly arrested after an altercation where reporters claim he threw a punch at Center Fielder Jimmy Collins, who allegedly spiked one of Marshall's teammates when he slid into first base. When Marshall was arraigned the following Tuesday, he was released with a $25 fine and a charge for disturbing the peace.
Marshall went on to pitch for the Chicago American Giants, Detroit Stars, and Kansas City Monarchs.
"Brown's Tennessee Rats..." Kansas City Sun, Kansas City, Missouri, Saturday, June 30, 1917, Page 8, Column 3
"Free-For-All Riot Marks Armour Game" Omaha World Herald, Omaha, Nebraska, Monday, une 30, 1919, Page 6, Column 6
"Rube Assigns Players to Giants" Chicago Defender, Chicago, Illinois, Saturday, March 20, 1920, Page 9, Column 5
"Jack Marshall" Omaha World Herald, Omaha, Nebraska, Tuesday, July 1, 1919, Page 8, Column 6
Negro league and Cuban League statistics and player information from Seamheads.com, or Baseball-Reference (Negro leagues)
1920 Chicago American Giants Calendar