Today armies around the world wear green or camouflage as their daily attire. But this had only sometimes been the case. For example, the U.S. Army wore blue denim shirts and pants from the 1920s to the early 1940s. The Army Denims, as they were called them, were used for field and work duties. So it was common to see soldiers in full battle gear with a nice indigo-colored uniform. Although they usually wore it over the regular wool uniform, mostly without something underneath.
The original fit of the Army Denims was very baggy, so they could quickly be put on over the wool uniform. In addition, the baggy fit provided lots of ventilation in the summertime, making the uniform not too hot.
This iconic uniform strongly inspired our Army Denim, and we have used a very nice Japanese Denim for recreation.