Maginot Line officials in Berlin and European neutral capitals provided indirect intelligence on German plans, including the build-up for BARBAROSSA in mid-1941 Useful information was gleaned from 1943 to 1944 about some secret Wehrmacht weapons research and about planned strategy and dispositions along the Atlantic Wall See also Hiroshima Suggested Reading: R Lewin, The American Magic (1982) MAGINOT LINE A French system of fortification-in-depth extending from the frontier with Belgium to the Swiss border It was first proposed in 1919 and was built in stages between 1929 and 1935 It represented the purest form of military deterrence in the 20th century It was named for André Maginot (1877–1932), minister for war Comprising a system of interlocking fields of fire from well-fortified sunken forts and casemates, it was much more solid and continuous than the Stalin Line built by the Soviet Union The end product was over 100 large works (“overages”) and 400 infantry positions; 152 revolving turrets; more than 1,500 fixed guns; and the equivalent in tunnels and underground barracks of the entire Paris Metro Belgium fortified along the Meuse independently of France, its works disconnected from the Maginot Line In 1936 Belgium renounced its security treaty with France and returned to reliance on legal neutrality, which would fail again in 1940 as it had in 1914 The French General Staff deemed the Ardennes Forrest a sufficient barrier to German armor that any thrust there would be so slow there would be sufficient time to react and counter it Meanwhile, French politicians recoiled at the expense of extending the Maginot Line and the logistical difficulties of constructing fortifications in such a densely populated area on the Franco– Belgian border For operational, alliance, and political and economic reasons, the Maginot Line thus stopped at the edge of the Ardennes That left 250 miles of exposed front, which ultimately invited a German flank attack around the northern end of the line After Germany remilitarized the Rhineland, the French partly extended the Maginot Line to cover the “Saar gap” and High Vosges From 1939 to 1940, during the “drôle de guerre,” a short second line was built 25 kilometers behind the main fortifications When completed, the Maginot Line comprised two fortified regions that blocked the main anticipated invasion routes from Germany: the Lauter Fortified Region (RF Lauter), and the Metz Fortified Region (RF Metz) As William Keylor has noted, “from a purely military point of view, the Maginot Line was brilliant in conception.” But its fine concepts and construction did not resolve the main problem that emerged from October 1936, when Belgium annulled a 1920 convention on mutual defense and instead retreated into the same formal neutrality it adopted before 1914 That left an exposed and weakly defended Ardennes gap and concealed threat to defense of the whole northern frontier of France When the great test of French fixed defenses came during the FALL GELB (1940) invasion, the Maginot Line worked: where assaulted, it stopped the German advance and prevented a deep invasion However, the main Panzer thrust went around the Line, through the “impenetrable” Ardennes French guns locked into fixed positions were thereby circumvented and many failed to fire a 695