Pewter WWI Tommy Helmet supplied on a pin with clasp.
During World War I thousands of miles of parallel trenches were dug along the western front. Trench warfare was necessary because the power, speed and accuracy of the weapons on both sides would have made it impossible to fight a battle in the open.
Various new weapons were introduced including hand grenades, poison gas, trench mortars, tanks and artillery barrages. These weapons caused the losses of millions of lives in the most bloody war the world has ever seen.