On August 10, 1934, in a small office with only 4 other Bureau officials, Clyde Tolson reported on a decision that would forever change J. Edgar Hoover's organization.  From the "Bureau Of Investigation" to the "Division Of Investigation" many of the Agents In Charge around the Country and Hoover himself had noticed a lot of confusion on the part of the public, the press, and general law enforcement with regard to what Hoover's organization did and did not have jurisdiction over.  Many still thought that the Prohibition Bureau was part of the Bureau Of Investigation.  The final culmination of the confusion came with outsiders thinking the "Division Of Investigation" was connected to the Department of the Interior's organization. 

Another name change was needed to set the FBI apart from the rest.  With Hoover's oversight of the meetings, Tolson's small gathering in August, 1934 changed it all.  No doubt one of the most, if not THE most, historic moments in Bureau history.
 
Read about it here