In 1929, to compete against Walt Disney's Mickey Mouse short cartoons, WB became interested in developing a series of animated shorts to promote their music. They had recently acquired Brunswick Records along with four music publishers for US $28 million (equivalent to $397 million in 2016) and were eager to promote this material for the sales of sheet music and phonograph records. Warner made a deal with Leon Schlesinger to produce cartoons for them. Schlesinger hired Rudolf Ising and Hugh Harman to produce the first series of cartoons. Schlesinger was impressed by Harman's and Ising's 1929 pilot cartoon, Bosko, The Talk-Ink Kid. The first Looney Tunes short was Sinkin' in the Bathtub starring Bosko, which was released in 1930.

More Info: en.wikipedia.org