In February 1942, Hitler's Minister for Weaponry and Munitions and chief civil engineer, Fritz Todt, had been killed in a plane crash, to which Speer was then appointed to take over all Todt's offices, which gave him responsibility for the German construction and energy industries. When Speer took on this role, he had soon realised that Germany was not prepared to fight a major world war. Nazi leaders did not have a clear military strategy and didn't understand how any war could affect the German economy. They believed that each campaign would be swift and easily won within a few weeks, and as a result only weapons with a limited use span would be designed
and produced, and a certain number of weapons were sent to each campaign. In 1941, German's weaponary, ammunition and mass production had been overwhelmed by the shear numbers of the American and British armies and by 1942, the blitzkrieg tactics had failed in Russia by the Germans and so Speer was able to attempt to create a long term or total war economy.He reorganised munitions production to use resources more efficiently.
Speer was highly successful as a arms manufacturer and within six months Speer had increased the German output of ammunition, guns and tanks. He had increased armaments by 300% with only a 30% increase in the labour force. Hitler gave Speer full authority over the plans to increase armaments production, and with this Speer realised that Germany now faced a long-term war and needed the effiency of the mass production from a limited number of standard items.
He stressed flexibility, initiative and improvisation. Hitler's respect for experts in general and personal regard for Speer in particular gave Speer unusual freedom. In May 1942 he was appointed one of two co-dictators of transport (with Milch). The railways became more efficient. Vast labour forces were sent to build roads for the army then invading the Soviet Union. In September 1943 (by which time the war was going very badly for Germany) Speer was promoted to become Reich Minister of Armaments and War Production.
Many of the labourers used in Speer's various activities were slave-workers from concentration camps, workers conscripted from occupied countries or prisoners of war. For the purely practical reason that healthy workers work harder, Speer tried to ensure that his workers at least received an adequate diet.
By 1944, Speer had nearly tripled the production of aircraft, artillery shells and tanks. Between 1942 and 1943, aircraft production increased from 14 000 to over 25 000; submarine production time reduced from twelve months to only two; armoured vehicle production increased from 140 000 to 370 000; medium and heavy tank production increased from 5500 to 12 000.
Because of these great increases in production, the war had been prolonged for another years thanks to Speer. By 1944, the war situation had become so bad for Germany that even Speer's success of production were unable to stay stable throughout the war and had gradually turned worse. Hitler ordered Speer to stop producing fighter aircraft in order to increase anti-aircraft gun production, and for the first time Speer had ignored his orders. He even had once admitted the chances of German victory to be low. During the last months of the war, Speer had spent it trying the save Germany's manufacturing base which under Hitler's scorched earth policy, was to be destroyed by retreating Germans. He had saved thousands of bridges, canals, communication and power installations in Germany as well the Netherlands, Czechoslovakia and Poland.