© Getty Images

A conventional war -

While Nazi Germany was certainly trying to win the Second World War, the regime was more willing to devote huge amounts of resources into maintaining a conventional war machine. Developing a nuclear weapons program simply wasn't a priority.

© Getty Images

World leaders in science -

This is despite Germany being a world leader in science and technology throughout the first half of the 20th century. German physicist Werner Karl Heisenberg (1901-1976), for example, was one of the main pioneers of the theory of quantum mechanics.

© Getty Images

Pioneers in their fields -

Another highly regarded theoretical physicist was Carl Friedrich von Weizsäcker (1912–2007).

© Getty Images

The Third Reich's pursuit of a nuclear weapon -

German chemist Otto Hahn (1879–1968) was one of the great minds in the fields of radioactivity and radiochemistry. Together, these three scientists would be instrumental in eventually persuading the leaders of the Third Reich to pursue a nuclear research program. Hahn, however, whose discovery of nuclear fission got the project started, actually never worked on it.

© Getty Images

Invasion of Poland -

The Nazis moved towards making an atomic bomb the same day Germany invaded Poland, on September 1, 1939. Shortly thereafter, the Uranverein, or "Uranium Club," was initiated.

© Getty Images

"Uranium Club" members -

Among the most influential people in the Uranverein was Kurt Diebner (1905–1964), a German nuclear physicist who directed the German nuclear energy program during the Second World War.

© Getty Images

Head of Reich Research Council -

German physicist Robert Abraham Esau (1884–1955) was head of the Reich Research Council and initiated the first meeting of the Uranium Club in 1939.

© Getty Images

Physics head -

German physicist Walther Gerlach (1889–1979) was the head of the physics section of the Reich Research Council.

© Getty Images

German nuclear energy program -

Another hugely influential member of the Uranium Club was Erich Schumann (1898–1985), who in fact ran the German nuclear energy program from 1939 to 1942.

© Getty Images

Albert Einstein -

One man not involved in Nazi Germany's quest for the bomb was Albert Einstein (1879–1955), who'd immigrated to the United States in October 1933.

© Getty Images

A letter to the president -

It was Einstein who in 1939 had sent a letter to President Franklin D. Roosevelt, the contents of which warned him that the Germans were probably working on a nuclear bomb.

© Getty Images

A dire warning -

Einstein had been asked to add his signature to the letter, which had been written by fellow physicist Leo Szilard (1898–1964). Hungarian-born Szilard had conceived the nuclear chain reaction in 1933. Realizing that the process could have a military application, he warned Einstein of the inherent danger. It was this letter that resulted in the Manhattan Project.

© Getty Images

Invasion of Denmark -

Meanwhile, Nazi Germany's conquest of Europe continued. In early 1940, Hitler invaded Denmark. It was at the the University of Copenhagen that Danish physicist Niels Bohr (1885–1962) had founded the Institute of Theoretical Physics.

© Getty Images

Under the eyes of the Gestapo -

Niels Bohr was one of the 20th century's leading physicists, and had made foundational contributions to understanding atomic structure and quantum theory. After Germany's invasion of Denmark, Bohr was spied upon by the Gestapo, as during the 1930s he'd assisted refugees in fleeing Nazism.

© Getty Images

Heisenberg and Bohr -

In 1941, Karl Heisenberg, who by now was heavily involved in the German nuclear weapons project, secretly met Bohr in the Danish capital, ostensibly to discuss the Uranium Club he was now leading for the Nazis. The two men are pictured together earlier, in 1934.

© Public Domain

The famous Heisenberg-Bohr meeting -

Debate still surrounds exactly what the two physicists discussed, though Bohr later claimed Heisenberg had boasted about an imminent German victory and how he would build the first atomic bomb. By all accounts, Bohr was shocked that Germany was pursuing nuclear weapons under Heisenberg's leadership. In 1943, Bohr and his wife escaped Nazi persecution in Denmark. He later joined the Manhattan Project.

© Getty Images

Germany's nuclear ambitions expand -

Meanwhile, the Nazi nuclear weapons program had expanded into three main efforts: Uranmaschine (nuclear reactor) development, uranium and heavy water production, and uranium isotope separation.

© Getty Images

The "Heroes of Telemark" -

In Norway, the Germans attempted to produce heavy water at the Vemork power station at the Rjukan waterfall in Telemark. Heavy water is used in nuclear reactors as a primary coolant. Its production was judged to be a serious enough threat that in 1943 the plant was destroyed by British commandos and Norwegian resistance fighters in a famous raid that made all involved the "heroes of Telemark."

© Getty Images

A non-nuclear Reich -

By 1943 with the war turning in favor of the Allies, Adolf Hitler and high-ranking Nazi military commanders turned their backs on the nuclear program, preferring instead to concentrate on the production of miracle weapons such as the V-1 and V-2 rockets. But how close had the Germans come in making an atomic bomb, and how would that have changed the outcome of the war?

© Getty Images 

The misfortunes of war -

The truth is the Nazis were nowhere near producing a bomb. In the first place, the Reich simply couldn't compete with the Allies in terms of scientific talent. Secondly, by 1943 resources and finances were severely stretched. Thirdly, Hitler simply didn't believe a weapon of this magnitude could be invented in the first place. In the words of Nazi armaments minister Albert Speer, Hitler was "filled with a fundamental distrust of all innovations."

© Getty Images

Luftwaffe failure -

Even if the regime had been successful in building the bomb, the only aircraft the Luftwaffe had available to carry such a weapon was the Heinkel He 177 Greif. But this notoriously accident-prone plane was nowhere near the strength or dimensions of the American B-59 bomber, the aircraft used to drop the nuclear devices over Japan.

© Public Domain

Lacking technical know-how -

And for the Germans to have equipped their V-2 rocket with a nuclear warhead, the device would have had to be no bigger than the size of a pineapple.

© Getty Images

But what if the Nazis had made an A-bomb? -

But even if Hitler had used atomic weaponry, would he have succeeded in ending the Second World War? At that point in the conflict, the US was safely out of reach of German bombers, so its own nuclear program would have continued.

© Getty Images

Out of range -

Similarly, the Soviet Union was manufacturing and stockpiling huge quantities of munitions in various far-flung locations across its vast land, well out of harm's way.

© Getty Images

Unlikely but scary scenario -

In the unlikely scenario of Hitler having dropped the bomb, chances are Great Britain would have capitulated. The Americans might then have declared a truce.

© Getty Images 

Stopping Stalin -

The Nazis would then divert all their forces to the Eastern Front to face down and either defeat the Red Army or negotiate a new non-aggression pact with Stalin.

© Getty Images

Nazi Germany wins the war -

Hitler would have won the Second World War, leaving the Nazi regime to reign supreme across Europe as the world's first nuclear power.

© Getty Images

The reality -

Of course, history ran a very different course. In the wake of Germany's surrender in May 1945, the Allies systematically dismantled various would-be nuclear installations, including the experimental nuclear pile at Haigerloch near Stuttgart (pictured).

© Public Domain

The Manhattan Project -

And what of the German scientists and physicists that escaped the Nazis in the 1930s? Many of these brilliant minds worked either directly or indirectly with Robert Oppenheimer on the Manhattan Project.

© Getty Images

The nuclear age -

And it was the Americans who ultimately devised the atom bomb and dropped the nuclear devices developed at Los Alamos on Hiroshima and Nagasaki on August 6 and 9, respectively, an event that ushered in a terrifying new nuclear age.

Sources: (History) (HistoryExtra) (Scientific American) 

See also: Atomic facts about the Manhattan Project

© Getty Images