From the War museum.ca/ Wikipedia
Did you know, that beginning in 1916, Canadian soldiers wore “Brodie helmets” during the First World War?
It is hard to believe but early in the First World War, none of the combatants provided steel helmets to their troops. Soldiers of most nations went into battle wearing cloth, felt, or leather headgear that offered no protection from modern weapons. Most soldiers on the front lines just wore fabric caps. The head wounds that many men suffered soon made it clear that moving to steel helmets would save lives but it would be April 1916 before Canadians began to be issued these pieces of protective equipment. The so-called Brodie helmet (The Brodie helmet is a steel combat helmet designed and patented in London in 1915 by John Leopold Brodie.) was made of a single piece of strong steel.
In modified form it became the Helmet, steel, Mark I in Britain and the M1917 Helmet in the U.S. Colloquially, it was called the shrapnel helmet, Tommy helmet, tin hat, and in the United States the doughboy helmet. Worn by Australians during WW2 and sometimes known as Panic Hat. It was also known as the dishpan hat, tin pan hat, washbasin, battle bowler (when worn by officers), and Kelly helmet. The US version, the M1917, was copied from the British Mk 1 steel helmet of 1916. The German Army called it the Salatschüssel (salad bowl) and some 7.5 million of them would be manufactured during the conflict.