Complex sentence: He was originally interred in Old St. Francis Cemetery, then he was reinterred on the grounds of the Poydras School in New Roads, Louisiana in 1891, when the old cemetery caved into the Mississippi River.
Split into simpler sentences: He was originally interred in Old St. Francis Cemetery. Then his remains were reinterred on the grounds of the Poydras School in New Roads, Louisiana in 1891, when the old cemetery caved into the Mississippi River.