After Matthew Perry's tour of duty comes to an end, his ability can instantly make you Suzerain of a city-state. It can be used to obtain a key buffer city-state, claim one that complements your strategy, or steal one that's crucial to an opponent's game plan. The only drawback is that the city-state needs to have at least one Coast or Ocean tile within its borders to allow Perry access.
During the Togukawa Shogunate (1633-1853), Japan operated under the policy of sakoku, having a “closed country.” During this time, nearly all foreigners were banned from the island, Japanese people were restricted from leaving, and trade and relations between Japan and the outside were curtailed. But the mid-19th century was the high era of European and American colonialism, when Western powers sought to open markets to their goods… by force, if necessary. And it was Commodore Matthew Perry who brought this force to Japan.
Perry was an old hand at such tactics, spearheading the use of overwhelming military presence for American expansion as well as the modernization of the American navy. He had previously commanded a ship that physically laid claim to the island of Key West (also claimed for Spain) by force and owing to that and subsequent service in the Mexican-American War, he rose rapidly in the ranks.
When Perry reached Japan, his actions were both blunt as well as informed by a partial understanding of Japanese society. He ignored Japanese borders and sailed into Edo Bay, near present-day Tokyo, firing blank shots from their massive new, state-of-the-art cannons. The Japanese, having been insulated from such heavy artillery during the sakoku period, were shocked, and rumors about “the black ship,” as Perry’s flagship was called, left an indelible mark on Japanese imaginations of the time. When Perry returned for a second visit, the Japanese signed whatever the Americans handed to them.
Japan could not hold out under such a threat, and Perry’s invasion of Edo Harbor, as well as the death of the shogun, marked an end to sakoku and the beginning of the outward-looking Meiji period.