<Li> May 22: Congressman Preston Brooks of South Carolina beats with a cane and incapacitates Senator Charles Sumner of Massachusetts on the floor of the U.S. Senate . In a speech in the Senate chamber, The Crime Against Kansas, Sumner ridicules slaveowners--especially Brooks's cousin, U.S. Senator Andrew Butler of South Carolina--as in love with a prostitute (slavery) and raping the virgin Kansas . Brooks is a hero in the South, Sumner a martyr in the North . </Li> <Li> In the 1856 U.S. presidential election Republican John C. Frémont crusades against slavery . The Republican slogan is "Free speech, free press, free soil, free men, Frémont and victory!" Democrats counter that Fremont's election could lead to civil war . The Democratic Party candidate, James Buchanan, who carries five northern and western states and all the southern states except Maryland, wins . </Li> <Li> Thomas Prentice Kettell, a New York Democrat, writes Southern Wealth and Northern Profits, a lengthy statistical pamphlet about the economies of the Northern and Southern regions of the country . The book receives wide acclaim among secessionists in the South and much derision from anti-slavery politicians in the North, even though some historians think Kettell intended it as an argument that the two regions are economically dependent upon each other . </Li> <Li> Filibusterer William Walker, in alliance with local rebels, overthrows the government of Nicaragua and proclaims himself president . He decrees the reintroduction of slavery . Many of Walker's men succumb to cholera and he and his remaining men have to be rescued by the U.S. Navy in May 1857 . </Li>

What specific issues and events led to the american civil war