He signed trade treaties with Britain and Japan, while his Cabinet reformed their departments and improved accountability, but these successes were overshadowed by political strife during his presidency. His popularity declined sharply in the Northern states after he supported the Kansas–Nebraska Act, which nullified the Missouri Compromise, while many whites in the South continued to support him. Passage of the act led to violent conflict over the expansion of slavery in the American West. Pierce's administration was further damaged when several of his diplomats issued the Ostend Manifesto calling for the annexation of Cuba, a document which was roundly criticized. He fully expected to be renominated by the Democrats in the 1856 presidential election, but was abandoned by his party and his bid failed. Pierce was popular and outgoing, but his family life was a grim affair, with his wife Jane suffering from illness and depression for much of her life. All of their children died young, their last son being gruesomely killed in a train accident while the family was traveling shortly before Pierce's inauguration.