Complex sentence: Night writing was a system of code that used symbols of twelve dots (2 wide and 6 high) designed by Charles Barbier in response to Napoleon's demand for a code that soldiers could use to communicate silently and without light at night.
Split into simpler sentences: Night writing was a system of code that used symbols of twelve dots arranged as two columns of six dots. It was designed by Charles Barbier in response to Napoleon's demand for a code that soldiers could use to communicate silently and without light at night.