One of the fundamental objectives (arguably the most fundamental objective) of the foreign policy of Nazi Germany (i.e. of Adolf Hitler) was acquisition of enough Lebensraum (“living space”) in Eastern Europe to make Germany self-sufficient in foodstuffs and other natural resources.
Obviously, the only way to acquire this Lebensraum was by waging an aggressive, colonial war against Czechoslovakia, Poland and the Soviet Union (roughly in that order). Which was a war crime – plain and simple.
It is very important, however, to understand the reason behind this fundamental objective. It did have historical roots in Ostsiedlung – medieval eastward migration and settlement of Germanic-speaking peoples from the Holy Roman Empire, especially its southern and western portions, into less-populated regions of Central Europe, parts of west Eastern Europe, and the Baltics.
The concept of Lebensraum was an important element of the Septemberprogramm prepared at the request of then German Chancellor Theobald von Bethmann-Hollweg in early September of 1914 when Germany, forced into the Great War by Serbia, Russia and France (roughly in that order) tried to figure out how to get the most out of that calamity (which some German government officials considered a “blessing in disguise”).
However, the most powerful driving force (by far) behind the Lebensraum objective was Hitler’s overwhelming desire to make sure that the horrors of the Blockade of Germany will never, ever happen again.
The Blockade of Germany (sometimes called the Blockade of Europe) was conducted by Great Britain from 1914 to 1919 in a (highly successful) attempt effort to restrict the maritime supply of goods to the Central Powers, which included Germany, Austria-Hungary and the Ottoman Empire. It is believed that this blockade was one of the key reasons behind eventual victory by the Entente powers (the other being the USA entering the war in 1917).
Apart from leading to shortages in vital raw materials such as coal and non-ferrous metals, the blockade also deprived Germany of supplies of fertilizer that were vital to agriculture.
This latter led to foodstuffs such as grain, potatoes, meat, and dairy products becoming so scarce by the end of 1916 that many people were obliged to instead consume ersatz products. Which led to widespread malnutrition and in many cases to outright hunger (due to shortages of even the ersatz foodstuffs).
Germany′s rationing system kept all but a few from actually starving to death, but a significant share of German population did indeed go hungry – for weeks, months and even years.
It is estimated that the blockade resulted in death toll from 424,000 (according to academic study done in 1928) to 763,000 (according to official data released by the German Board of Public Health in December 1918).
Although German soldiers on the frontline and in hospitals were well-supplied and thus did not suffer from malnutrition, Adolf Hitler obviously knew about the widespread hunger in his Fatherland.
Having experienced constant hunger himself (for more than a year in 1909-10) he vowed to do everything possible (and even humanly impossible) to make sure it never happens again to his Fatherland and his fellow Germans. And thus made Lebensraum the cornerstone of his foreign and military policy.
Consequently, it will be fair to conclude that the whole Lebensraum objective (and the resulting war crimes and crimes against humanity committed by Nazi Germany) were inspired and even determined by Great Britain who was solely responsible for the murder of 500,000 or so German civilians. Which was, obviously, a horrible war crime and crime against humanity.