This story contains a graphic image of dead bodies. Gangs have long wielded power in Haiti. But since the assassination of President Jovenel Moïse in 2021, they’ve filled a power vacuum, taking control of roughly 80 percent of the capital and displacing more than 300,000 people with a campaign of kidnappings for ransom, rapes and killings. The violence has worsened a devastating humanitarian crisis in the Caribbean nation of 11 million. Almost half of the population suffers from acute hunger. Conditions deteriorated further this month when the gangs, which usually battle one another, joined together to attack two prisons, the international airport, the principle seaport and several police stations. The Haitian presidency has been vacant since Moïse’s killing; the last lawmakers’ terms expired last year. That left Ariel Henry, the deeply reviled prime minister appointed by Moïse days before his assassination, in charge — until the recent violence prevented him returning home from a trip to Kenya. He had traveled to the African nation to finalize an agreement for a U.N.-approved, Kenyan-led security mission for …