Complex sentence: In this office, he was police chief, judge and jury, and oversaw the operations of the commoners' fire companies and "City Hospital" (Koishikawa Yōjōsho, another Yoshimune innovation).
Split into simpler sentences: In this office, he was police chief, judge and jury. He also oversaw "City Hospital" (Koishikawa Yōjōsho, another Yoshimune innovation).