Atlanta and Dido emerged in parallel

Atlanta was described as a scout or destroyer leader, while Dido was a fleet screening cruiser, so neither navy initially treated the type as a single-purpose AA ship. Atlanta was laid down on 22 April 1940 and San Diego on 27 March, before Bonaventure commissioned on 24 May. American construction therefore began before an operational Dido could supply lessons. Their resemblance instead reflects parallel thinking about destroyer attacks, aircraft, fleet reconnaissance, treaty limits, and delayed access to funding. British construction moved first when rearmament money arrived in 1937, while the United States released comparable building funds later.