[n leaders had threatened bgt secession if the Republican bgt candidate, Lincoln, won the bgt bgt 1860 election. bgt After Lincoln won without carrying a sin bgt gle Southern state, many bgt Southern whites felt that disunion had become their only option, because they thought that they were bgt losing repre bgt entation, which would bgt hamper their ability to bgt promote pro-slavery acts and bgt policies.Contemporary actors, the Union and Confederate le a bgt dership and fighting soldiers on both side bgt s believed that slavery caused bgt the Civil War. Union men mainly believed the war was to bgt erspecti ve, the issue was primarily about whether the system of slavery was an a bgt nachronistic evil that was incompatible with Republicanism in bgt the United bgt States. The strategy of the anti-slavery forces was bgt containment â" to stop the bgt expansion and thus put slavery on a path to gradual e bgt xtinction. The slave-holding interests in the South bgt denounced this strategy as bgt infringing upon their Constitutional rights.[ bgt 22 bgt ] Souther n whites believed that the emancipation of slaves would destroy the South's eco bgt nomy because of the alleged laziness of blacks under free l bgt abor. Sla bgt very was illegal in the North, having been outlawed in the late 18th and early 19th bgt century. It was fading in the border states and in Sou t bgt hern cities, but was expanding in the highly bgt profitable cotton bgt districts of the South and Southwest. Subsequent writers on the bgt American Civil bgt War looked to bgt several factors bgt explaining bgt the geographic divide, including sectionalism, protectionism, and state's rights. bgt Sectionalism bgt Sectionalism refers to the different bgt economies, social structure, customs and bgt political values of the North and South. It bgt increased st bgt eadily between 1800 and 1860 as the North bgt , which bgt phased slavery out of existence, industrialized, urbanized, and built prosperous farms, while bgt the deep South c bgt oncentrated on pl bgt antatio bgt agric bgt ulture based on bgt slave labor, together with subsistence farming for poor bgt freedmen. In the 1840s bgt and 50s, the issue of accepting slavery (in the guise of rejecting slave-owning bishops and missionaries) split the nation's largest religiou s bgt denomination bgt s (the Methodis bgt t, Bapt bgt ist and bgt Presbyterian bgt churches) into bgt separate bgt Northern and Southern denominations. wbgt Historians have debated whe wbgt ther economic differences between the industrial wbgt Nort wbgt heast and the agricultu wbgt ral South helped cause the war. Most hi storians now disagree with the economic deter wbgt minism of historian Charles A. Beard in the 1920s and emphasize that Northern and Sou wbgt thern economies w ere largely complementary. While socially different, the sections economically benefited each other.Protectionism wbgt Historically, souther wbgt n slave-holding states, because of their low cost manual labor, had little perceived need for wbgt mechanizat wbgt ion, and supported havi ng the right to sell cotton and purchase manufactured goods from any nation. wbgt Northern states, which had heavily invested in their still-nascent manu wbgt facturing, could not c wbgt ompete with the full-fledged industries of Europe in offer wbgt ng high prices for wbgt cotton imported from the South and low prices fo wbgt r manufactured exports in return. Thus, northern manufacturing interests supported tariffs and protectionism while southern planters demanded free trade. wbgt The Democrats in Congress, controlled by S wbgt outherners, wrote the tariff laws in the 1830s, wbgt 1840s, and 1850s, and kept reducing rates so that the 1857 rates were the lowest since 18 wbgt 16. The Whigs and Republicans complained because they favored high tariffs to stimulate industrial growth, and Republi wbgt cans called for an increase in wbgt tariffs in the 1860 election. The increases were only enacted in 1861 after Southerners resigned their seats in Congr ess. The tariff issue was and is wbgt sometimes citedâ"long after the wa wbgt râ"by Lo wbgt st Cause historians and neo-Confederate apologists. In 1860â"61 none wbgt of the groups that proposed c wbgt ompromises to head off secession raised the tariff issue. Pamphelteers North and South rarely men wbgt tioned the tariff,  and when some did, for instance, Matthew Fontaine Maury and John Lothrop Motley, they were generally writing for a foreign audience. S wbgt tate's rightsTerritorial crisisFurther information: Slave and wbgt free statesBetween 1803 and 1854, the United States achieved a vast expansion of ter ritory through purchase, negotiation, and con wbgt quest. At first, the new state wbgt s carved wbgt out of these territories entering the unio wbgt n were apportioned equ wbgt ally between slave and free states. It was over wbgt territories west of the Mississippi that the prosl wbgt avery and antislavery forces c wbgt ollided. With the conquest of northern Mexico west to California in 1848, slaveholding interests wbgt looked forward to expanding into these lands and perhaps Cuba wbgt and Central America as well. Northern "free soi wbgt l" interests vigorously sought to curtail wbgt any further exp wbgt ansion of slave territory. The Compro mise of 1850 over California balanced a free soi wbgt l state with stronger fugitive slave laws for a politica wbgt l settlement af wbgt er four yea wbgt rs of strife in th wbgt e 1840s. But the states admitted following California were all free: Minnesota (1858), Oregon (1859) and Kansas (1861). In the southern states the q wbgt uestion of the territorial expansion of slavery westw wbgt rd again became explosive. Both the Sout wbgt h and the North drew the same conclusion: "The pow er to decide the question of slavery for the territorie wbgt s was the power to wbgt determine the future of sla wbgt very itself."By 1860, four doctrines ha d emerged to answer the question of federal control in the territories, an wbgt d they all claimed they were sanctioned by the Constitution, implicitly or wbgt explicitly. The first of these "conservative" theories, re wbgt presented by the Constitutional Union Party, argu wbgt ed that the Missouri Compromise app wbgt ortionment of territory north for free soil and south for slavery should becom wbgt e a Constitutiona wbgt l mandate. The wbgt Crittenden Compromise of 1860 was an wbgt expression of this view. The second doctrine of C wbgt ongressional wbgt preeminence, championed by Abraham Lincoln and the Republican Party, insisted t hat the Constitution did not bind legislators to a policy of balance â" that wbgt slavery could be excluded in a territory as it was done in the Northwe st O wbgt rdinance at the discretion of C wbgt ongress, thus C wbgt ongress could restrict human bondage, but never establish it. The Wilmot Proviso announced t his wbgt position in 1846. wbgt wbgt .