Usami Chūhei (宇佐美 忠平, 1544 - 1616), sometimes referred to as Usami Munetō (宇佐美 宗任) was a samurai, statesman and bureaucrat from Wakasa Province in service to Sakai Hirochika. Chūhei was most famous for his assassination of Isshiki Hiromitsu, previously the head of the Oniwaban (御庭番, "garden keepers") at the bequest of Hirochika, then acting Left Hand of the Shōgun. Reportedly one of Japan's finest swordsmen, Chūhei was made head of the Oniwaban upon his assassination of Hiromitsu. In this position (which was effectively Head of Police for the period), Chūhei enacted reforms that converted the Oniwaban from simple informants and palace guards into a complex spy network across the country, referred to colloquially as "The Garden of Spiders' Webs" (蜘蛛の巣の庭).
Born in Wakasa Province in 1544, Chūhei was the son of a prominent jizamurai in service to the Sakai Clan. Chūhei's father's estate was positioned strategically on the border between Wakasa and Omi and thus he played an important role in the relations between the two provinces. Crucially, he lent his estate to Hirochika as a meeting point for those disaffected by the rule of Asai Sukemasa, or more accurately his new wife Fuchiyo. These retainers would become crucial for Hirochika's intrigue against Sukemasa and his subsequent usurpation of Omi in 1542.
In recognition of the usefulness of Chūhei's father, the Usami Clan was granted a small fiefdom on the border with Ise Province. Here Chūhei showed great ability in multiple Ko-ryū from a young age, and like his father showed an aptitude for tasks considered below most samurai, namely espionage and reconnaissance. Hirochika took notice and raised him to a position as a metsuke ("censor") for Wakasa in 1561, at the age of just 17. Crucially, this was just before the usurpation of the Ashikaga Shogunate at the hands of the Horiuchi Clan, who had manipulated their way into positions of prominence within the Shogunate Court before forcing Emperor Ōgimachi to declare the clan as the rightful enforcers of Imperial will. The response from the neighbouring clans was mixed, with some such as the Yusa and Ikeda declaring themselves loyal to the regime, whilst others such as the Kitabatake and the Kyōgoku opposing the overthrow.
War in Kyoto
Hirochika at first supported the coup, even going as far as to mass troops on the northern border of Ise Province, preventing Kitabatake Harumoto from acting against the shogunate for fear of an invasion. Chūhei meanwhile was ordered to bring a small force to Kyoto and "keep the peace", likely through the threatening and assassination of anti-Horiuchi factions within the capital. This small force bore the official title of Kyō kei gumi (京警組, "Capital Police Group") but was more commonly known by their nickname, Kage nagu-gumi (影殴組, "Shadow Strike Brigade" or "Shadow Assault Group").
The Kage nagu-gumi spent many weeks facing off in skirmishes across Kyoto against those forces loyal to Ashikaga Yoshiteru. Leading these forces were ten sword-students of Kitabatake Harumoto, sent as a gift years prior. They had formed another brigade, naming themselves the Kyō kei gumi in opposition. The two groups clashed repeatedly, mostly around the north-eastern sections of the capital. Yoshiteru had made his base here, in buildings constructed upon the remains of Sanjō Palace, which had been burned down during the Heiji Rebellion just over four-hundred years before. It is thought that he sheltered here deliberately, as the battle was as a result of a failed coup d'état. Most famously, the two groups clashed at two bridges entering Okazaki Seishojicho, the Niomon-dori and Nijo-dori bridges. A group of sixty Ashikaga supporters held off fifty Kage nagu-gumi samurai at the Niomon-dori bridge but were then shocked to hear that another group lead by Chūhei himself was crossing the Nijo-dori bridge to the north. The Ashikaga were unable to hold off the assault and three of Harumoto's sword-students perished in the fighting.
Left with little alternative, Yoshiteru chose to flee from the capital but was swiftly captured not far from Omi. He was then kept as a hostage of Sakai Hirochika. Meanwhile, in the capital, Chūhei had capitalised upon this victory, rooting out all remaining Ashikaga supporters and executing them. He also sent out smaller groups of samurai into the surrounding countryside to fortify outlying Temples and villages in preparation for a loyalist counter-attack. This vigilance proved prudent as a small force from the Kyōgoku clan of western Omi advanced upon Ōtsu. Expecting little resistance, the army of nearly two-thousand was surprised by the swiftness of Chūhei's response, drawing forces from as far away as Kiyomizu-dera on the outskirts of the capital. Outnumbered and outflanked within the city, the Kyōgoku army retreated south-east, constantly harried by Chūhei's forces. Having left reserves at Ishiyama-dera, he sent orders for them to block the crossings at the Seta River, trapping the Kyōgoku and subsequently annihilating them.