Who was responsible for the coming of the Civil War? Were strong personalities important? Could the war have been prevented?

The American Civil War was one of the bloodiest conflicts in national history, with the total number of casualties estimated at around 620,000 soldiers.  In this war, the northern states (also known as the Union) faced off against their southern neighbors, who had just recently seceded and formed the Confederate States of America.  When it comes to placing blame for the genesis of this war, though, neither the North or the South was fully at fault, for the Civil War arose, and some scholars would argue its inevitability, due to tensions surrounding the two sides' vastly differing economies and ideologies.

The northern economy prior to the Civil War was largely an industrial one, with factories and mills in cities such as Boston, New York, and Philadelphia.  This was due in part to the greater availability of natural resources (i.e. coal) within the region.  Additionally, the mileage of railroad track in the North was far greater than that of the South, enabling faster shipment of raw materials and finished goods.

The economy of the South, by contrast, was mostly based in agriculture, with the warm climate and fertile soil of the region enabling establishment of large-scale farms (often known as plantations) and the growth of profitable cash crops such as tobacco and cotton.  As a result, southerners saw very little need for industrialization, with fewer miles of railroad track than in the North and only ten percent of the population residing in urban communities.  Furthermore, while not all southern farmers owned slaves, this "peculiar institution" was seen as an inseparable component of the agricultural economy.

Another key difference between the northern and southern regions of the United States was that existing in their respective ideologies.  The southern way of life was deeply rooted in the concept of Jeffersonian agrarianism, which valued the virtue of "plain folk" over the more elite (and possibly corrupt) city populations, and held that an individual only needed to remain in one place and work on a farm.  By contrast, the North espoused the Whig ideology, one which valued modernization and the idea of a person "pulling themselves up by their bootstraps" and relying on their own abilities to overcome boundaries of self and location.

Some major personalities central to the Civil War's eventual breakout included Henry Clay, John C. Calhoun, Stephen Douglas, and Abraham Lincoln. 

Henry Clay, a member of the Whig Party, helped to engineer the Compromise of 1850, a series of bills passed to defuse political and sectional conflicts between free and slave states over the status of newly-acquired territories.

John C. Calhoun was a South Carolina senator who strongly supported slavery, and whose views on states' rights (powers exclusive to state governments), limited federal government, the opposition to high tariffs (allowing for free trade between nations), and nulllification (the right of states to declare federal laws null and void) influenced the South's decision to secede.

Stephen Douglas was a Northern Democratic senator from Illinois who assisted Clay with the Compromise of 1850, and is perhaps best known for his support of popular sovereignty, or the idea that states should be given the right to decide whether to allow or prohibit slavery.

Abraham Lincoln was an Illinois politician and lawyer, as well as the 16th President of the United States.  While his policies and actions as President helped to preserve the Union, his belief prior to and during the Civil War was that slavery could only be abolished as the result of constitutional amendments or military tactics (the Emancipation Proclamation being seen as an example of the latter).

In conclusion, the American Civil War was the result of major sectional, political, and ideological conflicts between the industrial North and the agrarian South, and the tensions which emerged from them became too great to be resolved politically or peacefully.