War can have a huge effect on a nation’s demographics, but not always in the way you would expect.

The First World War (1914-1918) was the world’s first total war. In the bitter struggle, governments mobilized their entire populations to help the war effort. The mobilization of women, as well as the absence of millions of men, meant plummeting birthrates. 

In no major country was the war more total or birthrate decline steeper than in Germany. An estimated 3.2 million fewer children were born in Germany during the four years of the war. For comparison, France saw a (somewhat milder) 1.4 million fewer children. Yet Germany’s demographic problems didn’t stop there. Birthrates continued to decline after the war, until about 1932. 

As you can see from the above picture, the population born in the years 1915-1919 was roughly half of what it should have been, given pre-war numbers. The post-war numbers also showed about 250,000 fewer births annually than had been the case in the past, likely due to long-term population transition. Imagine for a moment what that sort of population drop would affect everyday life. Children born in 1915 would have learned in classes half the size of the ones their older siblings had used. Playgrounds would have emptied, and never-worn baby shoes would have been a common sight in stores.

Even during peacetime, such population loss would have rippled through society, causing labor shortages, housing shrinkage, and economic troubles, a sort of reverse baby boom. Just like the baby boom, the German baby bust had an ‘echo’ in the mid-late 1940s, when birth rates again dropped.

Germany’s population problem would become still more serious, however, when Adolf Hitler launched Europe into another catastrophic world war. By that time, the drop in birth rates had left an enormous hole in Germany’s military-aged population. By 1939, the start of the war, the children born during the First World War (i.e. the generation about half the size it should have been) was aged 21-25, the ideal age for military service. (The average American serviceman was 26 during World War II). Germany had lost 1.6 million potential soldiers before the war even began. The crucially important population of Germans aged 21-34 was about 15% smaller than it would have been if not for the plummeting birthrate during the First World War.

The German shortage of young men and women undoubtedly held back the German military and economy during the war. To resolve the shortfall, the Nazis resorted to a variety of cruel measures, such as forcing prisoners of war to work as laborers (thus freeing up Germans). The infamous work camps of the Holocaust also represented, in part, an effort to make up for the shortage of German manpower with what amounted to slave labor. Finally, Germany’s manpower shortage caused it to send boys and old men into combat in the final months of the war.

Even titanic demographic changes have a tendency to hide in plain sight, since they generally occur gradually and, to historians, take the form of dry charts and graphs. We must not forget, however, the immense significance these changes would have had, both for the German public and for the German war effort from 1939-1945.