There has been a fair bit of discussion as to how the German stahlhelme was introduced into the trenches early on. Here is a brief account of how it was done in the CEF. This excerpt is from one of the best original survivor memoirs ever written by a member of the CEF. "The Journal of Private Fraser" Canadian Expeditionary Force 1914-1918, CEF Books 1998 ISBN 1-896979-28-9:
"I forgot to mention, that we are now wearing steel helmets. We started in with one to each bay, changing over from guard to guard. These helmets were treated as trench stores and consequently were turned over to the relieving battalion. There was no ventilation in the first issue and the head perspired freely. In time the helmet became part of the soldier's equipment and as soon as he came within range of shell fire he had to don it." pg 69.
"I forgot to mention, that we are now wearing steel helmets. We started in with one to each bay, changing over from guard to guard. These helmets were treated as trench stores and consequently were turned over to the relieving battalion. There was no ventilation in the first issue and the head perspired freely. In time the helmet became part of the soldier's equipment and as soon as he came within range of shell fire he had to don it." pg 69.