redeployed to the Mongolian-Manchurian border to fight in the Battle of Khalkhin Gol, but when this conflict ended, in September 1939, the BR.20s were progressively withdrawn and replaced by the Ki-21. Despite having been phased out from operational service, the BR.20 was allocated the Allied reporting name "Ruth". Second World War France Following Nazi Germany's invasion of France in May 1940, and with German forces pushing deep into France, Italy declared war upon both France and the United Kingdom on 10 June 1940. At this time, only four wings operated BR.20s compared to the 14 wings equipped with SM.79s, with 172 Cicognas being in service with the Regia Aeronautica including those not yet delivered to operational squadrons. The units equipped with the Cicogna were the 7°, 13°, 18° and 43° Stormo (Wing), all of which were based in Northern Italy; the decision to base the type in the north of the country was due to the general strength of the aircraft and its excellent flight performance upon encountering turbulence. The aircraft of the 7°, 13° and 43° Stormo fought in the brief campaign against France. On the night of 12 June 1940, eight bombers from 13° attacked Toulon dockyard. The next day, 10 Fiat BR.20s dropped bombs on Hyères and Fayence airfields; two aircraft (commanded by Catalano and Sammartano) were shot down and one was badly damaged. The same day, 28 BR.20s from 43° and 7° Stormo bombed Toulon again, with no losses. On 15 June, one BR.20M (Matricola Militare MM. 21837) of the newly formed 172a Squadriglia Ricognizione Strategica Terrestre based on Bresso airfield, was shot down over Provence by Dewoitine D.520s, the French air defenses in the south having not been defeated by the German attack in the north. Small-scale air raids continued until the French surrender, with many BR.20s also used in support for the Army – bombing Briançon, Traversette and Cap San Martin fortresses on the Alps – and as reconnaissance aircraft. At the end of the French campaign, five BR.20s had been lost and 19 airmen killed. In the immediate aftermath of the campaign, the type resumed normal training and base duties. Britain It was during the Battle of Britain, in which Axis aircraft flew over the English Channel to directly challenge the British mainland itself, that the BR.20 showed its limitations for the first time. On 10 September 1940, the Corpo Aereo Italiano was