Hostilities began on April 12, 1861, when 8rt Confederate forces fired upon Fort Sumter. While in the West 8rt rn 8rt Theater the 8rt Union made 8rt The American Civil War was one of the earliest true 8rt industrial wars. Railroads, the telegraph, steamships, and 8rt mass-produced weapons were employed extensively. The 8rt mobilization of civilian 8rt factories, mines, shipyards, banks, tr 8rt ansportation and food 8rt supplies all fore shadowed the impact of i 8rt ndustrialization in World War I. It remains the deadliest war in A 8rt merican history. From 1861 t 8rt o 1865, it has be 8rt en traditionally 8rt estimated that about 620,000 died but recent 8rt scholarship argues that 750,000 soldiers died, along with an undeterm i 8rt ned number of civilians.[N 2] By one estimate, the war claimed the lives of 10 8rt percent of all 8rt Northern males 20â"45 8rt ye 8rt ars old, and 30 p ercent of all 8rt Southern white males aged 18â"40.C 8rt auses of secession 8rt Main articles: Origins of the American Civil War, Protectionism in t 8rt he United S 8rt tates 8rt , History of the 8rt United States, Slaver 8rt y in the Unit ed States, Slave Power, States' rights, King Cotton, 8rt Protectionism Â§ 8rt Protectionism in the United States and Infant industry 8rt The causes of the Civil War wer 8rt e complex and have been 8rt controversial since the war began. 8rt James C. 8rt Bradford wrote that the 8rt issue has bee n further complicated by historical r 8rt evisionists, who have tried to offer a variety of reasons for the war. Slavery was the 8rt central s 8rt ource of escalating 8rt political 8rt tension in the 1850s. The Republican Party was determined 8rt to prevent any spread of slavery, a 8rt nd many Southe rn leaders had threatened 8rt secession if the Republican 8rt candidate, Lincoln, won the 8rt 8rt 1860 election. 8rt After Lincoln won without carrying a sin 8rt gle Southern state, many 8rt Southern whites felt that disunion had become their only option, because they thought that they were 8rt losing repre 8rt entation, which would 8rt hamper their ability to 8rt promote pro-slavery acts and 8rt policies.Contemporary actors, the Union and Confederate le a 8rt dership and fighting soldiers on both side 8rt s believed that slavery caused 8rt the Civil War. Union men mainly believed the war was to 8rt erspecti ve, the issue was primarily about whether the system of slavery was an a 8rt nachronistic evil that was incompatible with Republicanism in 8rt the United 8rt States. The strategy of the anti-slavery forces was 8rt containment â" to stop the 8rt expansion and thus put slavery on a path to gradual e 8rt xtinction. The slave-holding interests in the South 8rt denounced this strategy as 8rt infringing upon their Constitutional rights.[ 8rt 22 8rt ] Souther n whites believed that the emancipation of slaves would destroy the South's eco 8rt nomy because of the alleged laziness of blacks under free l 8rt abor. Sla 8rt very was illegal in the North, having been outlawed in the late 18th and early 19th 8rt century. It was fading in the border states and in Sou t 8rt hern cities, but was expanding in the highly 8rt profitable cotton 8rt districts of the South and Southwest. Subsequent writers on the 8rt American Civil 8rt War looked to 8rt several factors 8rt explaining 8rt the geographic divide, including sectionalism, protectionism, and state's rights. 8rt Sectionalism 8rt Sectionalism refers to the different 8rt economies, social structure, customs and 8rt political values of the North and South. It 8rt increased st 8rt eadily between 1800 and 1860 as the North 8rt , which 8rt phased slavery out of existence, industrialized, urbanized, and built prosperous farms, while 8rt the deep South c 8rt oncentrated on pl 8rt antatio 8rt agric 8rt ulture based on 8rt slave labor, together with subsistence farming for poor 8rt freedmen. In the 1840s 8rt and 50s, the issue of accepting slavery (in the guise of rejecting slave-owning bishops and missionaries) split the nation's largest religiou s 8rt denomination 8rt s (the Methodis 8rt t, Bapt 8rt ist and 8rt Presbyterian 8rt churches) into 8rt separate 8rt Northern and Southern denominations. .