Complex sentence: Kearny was sent to France, in 1839, to study cavalry tactics, first attending school at the famous cavalry school in Saumur, France, and then participating in several combat engagements with the "Chasseurs d'Afrique" in Algiers.
Split into simpler sentences: Kearny was sent to France in 1839 to study cavalry tactics, first attending school at the famous cavalry school in Saumur. He participated in several combat engagements with the "Chasseurs d'Afrique" in Algiers.