The French Navy (Marine Nationale) created a series of heavy cruiser designs in 1939 to follow the Algérie but free of the limitations imposed on warship construction by the London Naval Treaty and Washington Naval Treaty.

At the outbreak of the Second World War, all ships under construction that could not be finished in the short term were suspended, and their designs reviewed.

French Navy officials in the late 1930s, in addition to their concern over the growth of the Italian Regia Marina, were also influenced by the news of Germany laying down five (nominally) 10,000-ton heavy cruisers armed with 20.3 cm guns which further impelled the need for newer, more heavily armed cruisers.

Both designs would be based on Algérie, such as a flush deck, bridge tower structure and protection.

The major innovation of the C5 over the C4 was the adoption of three triple mounted 203 mm (8 in) guns., which was influenced by the De Grasse-class light cruisers.

A single gun prototype of the ACAD was mounted on Amiens in 1939 which provided covering anti-aircraft fire for retreating British Expeditionary Force during the Battle of Dunkirk.

Absent from the A3 design, four quadruple Hotchkiss M1929 machine gun positions were located on the corners of the shelter deck, as with the Algérie.

With the outbreak of war in Europe on 1 September 1939, all ships under construction that could not be completed in the short term were suspended and were to be reviewed, including the C5 program.