How could a member of the military communicate silently and without light?

Braille was based on a tactile military code called night writing, developed by Charles Barbier in response to Napoleons demand for a means for soldiers to communicate silently at night and without light. In Barbiers system, sets of 12 embossed dots encoded 36 different sounds. It proved to be too difficult for soldiers to recognize by touch and was rejected by the military.

Which branch of the military do babies join?

The infantry!