During World War I, the word "portable" still applied to the military's truck-sized bread mixers, which could make six thousand loaves of various sizes, weights, and shapes in just an hour. In addition to speeding up the process of baking, this machine was less cumbersome and easier to operate than its predecessors. A crew of five men could do all the work, while earlier arrangements required a crew of 112 to produce the same amount of bread by hand. To use it, you would pour the ingredients into an electrically driven dough mixer. Once mixed, the dough would be kneaded and divided while passing through a small belt conveyer. As a hygienic measure, finished loaves would drop directly into baking pans.
Read the full story in The Portable Army Bread-Mixer