These eyeglasses would save your head

The Type 91 periscope used by the Japanese military during World War II had several interesting aspects and historical significance:

Compact Design: Its compact size made it highly portable, allowing soldiers to easily carry it and set it up in confined spaces like trenches or foxholes.
Mirror System: The periscope used a series of mirrors to reflect and transmit images. The optical system within the periscope allowed for a limited but useful field of view.
Utility in Trench Warfare: It was specifically designed for trench warfare, enabling soldiers to observe enemy movements and positions without exposing themselves to direct fire. This helped in reconnaissance and maintaining situational awareness on the battlefield.
Versatile Use: While primarily used in trench warfare, the Type 91 periscope was also utilized in other scenarios where observation from cover was necessary, such as urban combat situations or defensive positions.
Manufacture and Use: It was produced in significant numbers and distributed among infantry units. Its relatively simple construction made it easier to manufacture compared to more complex optical devices of the time.
Military Legacy: The Type 91 periscope, along with other Japanese military equipment of that era, is a part of the historical legacy of World War II and serves as a reminder of the technological innovations and strategies employed during that period.
Collectible Item: Today, surviving Type 91 periscopes are considered collectible military artifacts, sought after by collectors and historians interested in World War II memorabilia and equipment.
This periscope, though seemingly a simple device, played a significant role in providing vital information to Japanese soldiers while keeping them relatively safe from enemy fire. Its design and functionality showcase the innovation and practicality employed in developing tools for trench warfare during that era.