Short answers, pulled from the story.
Jacob Warner was born in London, Ontario, on the 2nd of August 1892, to Polish-Jewish immigrants who spoke Yiddish and fled pogroms in Congress Poland. His father Benjamin Warner originally named Wonskolaser worked as a cobbler before moving to the United States in 1888 to settle in Youngstown, Ohio.
Sam Warner pushed the family into film production with the invention of sound and urged Harry to sign with Western Electric to develop Vitaphone technology in 1925. The studio released The Jazz Singer in 1927 which became the first feature-length talking picture and brought the studio $3 million in profits from a $500,000 investment.
Warner Bros. released Confessions of a Nazi Spy in 1939 which was recommended by FBI Director J. Edgar Hoover and drew on the real-life experiences of Agent Leon G. Turrou. The studio produced more pictures about the war than any other studio including patriotic musicals such as This Is the Army and Yankee Doodle Dandy and the Academy Award winning Best Picture Casablanca in 1943.
In July 1956 Jack secretly organized a syndicate that purchased control of the company while Harry and Albert Warner were unaware. Jack became the company's largest stockholder and appointed himself as the new company president before Harry died on the 27th of July 1958.
Jack served as a friendly witness before the House Un-American Activities Committee in 1947 and voluntarily named screenwriters who had been fired as suspected communists or sympathizers. Former studio employees named by Warner included Alvah Bessie Howard Koch Ring Lardner Jr. John Howard Lawson Albert Maltz Robert Rossen Dalton Trumbo Clifford Odets and Irwin Shaw.
Jack died of a heart inflammation on the 9th of September 1978 at the age of 86 after suffering a stroke in 1974 that left him blind and enfeebled. He left behind an estate estimated at $15 million with much of it bequeathed to his widow Ann and $200,000 to his estranged son Jack Jr.