speed: the first production aircraft flew less than a year after being ordered and was in service before the end of 1939. As with the Potez 630, the Bre 691 was beset with engine difficulties. Hispano-Suiza had decided to concentrate on its V12 liquid-cooled engines and the 14AB engine was unreliable. The French authorities decided to limit the Bréguet 691's production run to 78 aircraft, instead of 100. Instead, orders were placed for another version, the Bre 693 powered by Gnome-Rhône 14M radials. Apart from the changed engines, which were of slightly smaller diameter, the two types were virtually identical. Orders for the Bre 691 were switched to the new type and more than 120 of the latter had been completed by the time of France's defeat. Late production versions of the Bre 693 introduced propulsive exhaust pipes that improved top speed by a small margin as well as, according to some sources, a pair of additional machine guns in the rear of each engine nacelle. Belgium ordered 32 licence-built copies but none were completed before the Belgian collapse. French engine makers had even greater difficulties than airframe manufacturers in keeping up with the frantic demands from 1938, and in 1939 the French government decided that all combat aircraft had to be adapted for British and US engines. Fewer than 250 Bréguet 690 series aircraft were completed. The Armée de l'air received only 211 examples: 78 Bre.691s, 124 Bre.693s and nine Bre.695s but the Germans captured several complete or near-complete aircraft at the factories. Operational history A small experimental unit had been experimenting with ground-attack tactics since 1937, initially in outdated biplanes such as the Potez 25, then in ANF Les Mureaux 115 monoplanes. Eventually, the Armée de l’Air concluded that low-altitude level bombing was more suitable than dive-bombing for engaging enemy vehicles and artillery over the battlefield. The chosen tactic consisted in a nap-of-the-earth approach at maximum speed, followed by a strafing run or the delivery of time-delayed bombs directly over the target. French commanders widely considered this tactic as safe for the attackers, as anti-aircraft weapons then in service would be inefficient. The French Army was not using anti-aircraft autocannons at the time (the 25 mm Hotchkiss and 20 mm Oerlikon cannons were issued only later), relying instead on rifle-calibre machine guns and slow-firing 75 mm (2.95 in) guns. In late 1939, two squadrons transferred from level bomber