In late 1939, two squadrons staffed with volunteers from level bomber units were gathered in the small airfield near Vinon-sur-Verdon, where they began their operational training. As Bréguet 691s were not available yet, the crews flew the Potez 633 light bomber. When they were eventually delivered, the little Bréguet were popular with their crews, although the unreliable engines in the Bre 691 affected aircraft availability rates, and undercarriage failures proved especially troublesome. Only in March 1940 were the first combat-worthy Bre. 693s delivered, and there were now five squadrons to equip: GBA I/51, GBA II/51, GBA I/54, GBA II/54, and GBA II/35 (GBA stood for "Groupe de bombardement d'assaut" – assault bomber squadron), with a theoretical complement of 13 aircraft each.