Question: What gave the Allies the advantage during World War 2?
About the article "World War II", section "Home fronts and production".

Candidate passages:
Its railyards were bombed by the Allies during World War II. 
After World War II, the U.S. kept the M4A3E8 "Easy Eight" in service with either the 76 mm gun or a 105 mm howitzer.
The Sherman remained a common U.S. tank in the Korean War.
Despite no longer being the primary US tank, it fought alongside the M26 Pershing and M46 Patton.
The M4A3E8 Sherman and T-34-85 were comparable and could destroy each other when hit, although the use of HVAP shells gave the Sherman a firepower advantage.
The Sherman had better optics, which gave it a better chance of scoring a first round hit.
The Army replaced them with Pattons during the 1950s.
The U.S. continued to transfer Shermans to its allies, which contributed to widespread foreign use. 
About two months after he was stripped of power, Benito Mussolini was rescued by the Germans in Operation Eiche ("Oak").
The Germans re-located Mussolini to northern Italy where he set up a new Fascist state, the Italian Social Republic ("Repubblica Sociale Italiana" or RSI).
Many Italian personalities joined the RSI, like General Rodolfo Graziani.
The Allied armies continued to advance through Italy despite increasing opposition from the Germans.
The Allies soon controlled most of southern Italy, and Naples rose against and ejected the occupying German forces.
The Allies organized some Italian troops in the south into what were known as "co-belligerent" or "royalist" forces.
In time, there was a co-belligerent army (Italian Co-Belligerent Army), navy (Italian Co-Belligerent Navy), and air force (Italian Co-Belligerent Air Force).
These Italian forces fought alongside the Allies for the rest of the war.
Other Italian troops, loyal to Mussolini and his RSI, continued to fight alongside the Germans (among them were the Esercito Nazionale Repubblicano, the National Republican Army).
From this point on, a large Italian resistance movement located in northern Italy fought a guerrilla war against the German and RSI forces.
Winston Churchill had long regarded southern Europe as the military weak spot of the continent (in World War I he had advocated the Dardanelles campaign, and during World War II he favored the Balkans as an area of operations, for example in Greece in 1940 and so on).
Calling Italy the "soft underbelly" of the Axis, Churchill had therefore advocated this invasion instead of a cross-channel invasion of occupied France.
But Italy itself proved anything but a soft target: the mountainous terrain gave Axis forces excellent defensive positions, and it also partly negated the Allied advantage in motorized and mechanized units.
The final Allied victory over the Axis in Italy did not come until the spring offensive of 1945, after Allied troops had breached the Gothic Line, leading to the surrender of German and RSI forces in Italy on 2 May shortly before Germany finally surrendered ending World War II in Europe on 8 May.
Mussolini was captured and killed on 28 April 1945 by the resistance while attempting to flee. 
In Europe, before the outbreak of the war, the Allies had significant advantages in both population and economics.
In 1938, the Western Allies (United Kingdom, France, Poland and British Dominions) had a 30 percent larger population and a 30 percent higher gross domestic product than the European Axis (Germany and Italy); if colonies are included, it then gives the Allies more than a 5:1 advantage in population and nearly 2:1 advantage in GDP.
In Asia at the same time, China had roughly six times the population of Japan, but only an 89 percent higher GDP; this is reduced to three times the population and only a 38 percent higher GDP if Japanese colonies are included.
Though the Allies' economic and population advantages were largely mitigated during the initial rapid blitzkrieg attacks of Germany and Japan, they became the decisive factor by 1942, after the United States and Soviet Union joined the Allies, as the war largely settled into one of attrition.
While the Allies' ability to out-produce the Axis is often attributed to the Allies having more access to natural resources, other factors, such as Germany and Japan's reluctance to employ women in the labour force, Allied strategic bombing, and Germany's late shift to a war economy contributed significantly.
Additionally, neither Germany nor Japan planned to fight a protracted war, and were not equipped to do so.
To improve their production, Germany and Japan used millions of slave labourers; Germany used about 12 million people, mostly from Eastern Europe, while Japan pressed more than 18 million people in Far East Asia.
There is evidence that many U.S. allies have been alienated by a unilateral approach.
Allies signaled dissatisfaction with U.S. policy in a vote at the U.N. Brzezinski counsels listening to allies and exercising self-restraint.
During the Yugoslav Wars in the 1990s, the US opposed Serbia, a country that was not against the US and capitalist ideals during the Cold War and an ally during both World Wars in which the Serbs saved the lives of many American pilots who flew missions over the Balkans.
Instead, the US supported Kosovo Albanians and Croatians, both who were never true allies of the US and had even fought against the US during World War 2.