When was the old steel diving helmet mostly replaced?
Metal helmets are still in use by professional divers. Many consider the metal helmet to be safer than SCUBA gear.
Originally Germany entered the war in 1914 with a leather helmet with a spike atop it, called the Pickleshube(sp?). This was replaced in 1916 by their coal scuttle shaped M1916 all steel helmet. France produced their own all steel Adrian helmet, and the US adapted the British all steel Tommy helmet (also known as the Brodie, and later the Model 1917 "dough-boy" helmet).
Metal parade helmets based upon British (pith helmets) & modified German (Prussian) designs were in use in the 1880's by US Army personnel. However, practical protective steel helmets were not issued until WW1...the model 1917 British style "dough-boy" helmet. This helmet was used from 1917 until 1942; when it was replaced by the M-1 steel helmet (steel pot). The M-1 steel helmet fought it's last war in Vietnam.
They were called "Helmets". The US Helmet was a steel helmet and a separate liner and was referred to as Model M-1. The liner was molded from fiber board and it had the straps riveted into it. The straps were adjustable to allow it to fit many sizes. The Liner had a thin chin strap. The helmet had a larger cloth strap.