Centuries before the Great War, most coordinations within the battlefield happened through signaling, mostly by waving flags or banners. While this was undoubtedly effective, it had the drawback
of being easily read or anticipated by an enemy with deep understanding of the code. By the XXth century, with dedicated spies gaining intelligence, this was
rather possible; so coordination without visual signaling was needed.
New military tactics also called for more precise coordination between units. For example, in order for infantry to advance under the cover of artillery, both forces needed to be aware of
the time the bombardment would begin, as to avoid friendly fire. All of this required that soldiers could reliably read and assess the passage of time in their own
But pocket watches, the most common at the time, were ill-suited for this task. First, they were rather fragile and would easily fail or break when exposed to
the elements, hence the need to be protected in a pocket. Second, it was rather cumbersome to have to reach out for your pocket, bring out the watch and then open it to read the time. This
military challenge led first to the creation of the trench watch (a sort of pocket and wristwatch hybrid), and then to the mass adoption of the wristwatch, which
was an smart alternative to the pocket watch, and gave the soldiers easy access to the time.