Complex sentence: He left Lieutenant of minors in the School of Artillery and Engineers of Chalons-sur-Marne in 1793 and soon after became Engineer Captain in the Army of the Rhine in 1794.
Split into simpler sentences: He left Lieutenant of minors in the School of Artillery and Engineers of Chalons-sur-Marne in 1793. Soon after, Haxo became Engineer Captain in the Army of the Rhine in 1794.