Besides mud and artillery, WWI armies had another critical condition to consider – the cold. Fighting in the cold was a war unto itself.

Soldiers, sailors and marines in World War I used a variety of visual and auditory signals to communicate over the noise of battle – including the trusty whistle.

Clad in his American flag suit, Uncle Sam has long been popular as the personification of the United States. His most famous depiction comes from a 1917 WWI poster.

Using it as food, fiber, medicine and recreation – even playing a role in religious rituals and warrior traditions – humanity has known cannabis for thousands of years.