The place of Champs mentioned on the postcard is likely Champs-sur-Marne, a small town east of Paris in an area where fierce fighting occurred in 1870 between Prussians and the French. Champs is only about 5 miles from Bry-sur-Marne and Champigny, where one of the most famous battles of the Franco-Prussian war took place.
The 2. Eskadron was garrisoned in Champs in the summer of 1871. So presumably, the seated Rittmeister is squadron commander and later Oberst and regimental commander of Ulanen-Regiment. Nr. 4, Werner von Schönfeldt.
Glenn, you really bring these wonderful slices out of time fully back to life with your research. Rittmeister von Schonfeldt would be amazed, and I hope flattered, to be so remembered in our time. Well done - yet again!