The helmets of the Second World War were based on previous military experience and doctrine. I happen to own many of these helmets so I’ll give you a fashion show starring yours truly.
For example, the British helmet was the same as the one worn in the First World War.
During the First World War, a majority of casualties were a result of artillery shrapnel to the head. So, the British army need a design that would protect the user from overhead debris. Thus, the Brodie Helmet was born. The Brodie helmet was design specifically to protect the user from over head shrapnel puncturing the skull.
The goal of the Brodie helmet remained. Protect the user from overhead shrapnel.
The American helmet was vastly different from the Brodie helmet (which they used in World War 1). The helmet was built to act as a Jack of all trades type of the helmet world. The M1 Helmet was built to protect both the user’s frontal and occipital lobe from frontal shrapnel.
(NATO issued Belgian M1, same design)
The Soviet helmet wasn’t issued large scale until the later years of the war. At the outset of the war, Soviet units were rarely issued with helmets, opting out for the pilotka cap.
(Note no Soviet soldier has a helmet)
However, as the war dragged on and the need for helmets increased, the Soviets produced more and more helmets to protect from shrapnel. Soviet industry churned out millions of these helmets, equipping almost all combat divisions. However, as the tide turned against the Germans, mobility became an issue, so helmets became less common on the battlefield.
As you can see here, there is a mix of Ushankas and pilotka caps.
(I do own a Pilotka, but it’s at my fathers, so here’s an officer’s visor. Doesn’t offer much protection from shrapnel either way.)
The German helmet however, is the best design in my opinion. The WW2 Stahlhelm was based on the WW1 Stahlhelm. The Stahlhelm was issued to German soldiers to protect the frontal and occipital lobes from shrapnel. Along with protection of the lobes, the ears and top of the head were also protected.
Stahlhelm proved to be a very effective design, drastically reducing head-related casualties among German soldiers. So, the German forces kept the design, and improved on the helmet’s design.
The profile was lowered, the lugs on the sides were removed, and the sides slimmed down. Visibility improved and the cost was reduced.
The helmet protected all the important parts of the brain, while keeping the helmet light and easy to see out of. However the helmet was expensive to produce, making it a burden on the German war economy. It took multiple sheets of metal as opposed to just one. However, I would be comfortable going to war with a Stahlhelm.
The Chinese were supplied with Stahlhelms.
Even after the war, West German soldiers were issued the Stahlhelm.