' "Attempts by the Confederate government to settle its differences with the Union were spurned by Lincoln, and the Confederacy felt it could no longer tolerate the presense of a foreign force in its territory. Believing a conflict to be inevitable, Lincoln ingeniously devised a plan that would cause the Confederates to fire the first shot and thus, he hoped, inspire the states that had not yet seceded to unite in the effort to restore the Union.

On April 8, Lincoln notified Gov. Francis Pickens of South Carolina that he would attempt to resupply the fort. The Confederate commander at Charleston, Gen.P.G.T. Beauregard, was ordered by the Confederate government to demand the evacuation of the fort and if refused, to force its evacuation. On April 11, General Beauregard delivered the ultimatum to Anderson, who replied, "Gentlemen, if you do not batter the fort to pieces about us, we shall be starved out in a few days." On direction of the Confederate government in Montgomery, Beauregard notified Anderson that if he would state the time of his evacuation, the Southern forces would hold their fire. Anderson replied that he would evacuate by noon on April 15 unless he received other instructions or additional supplies from his government. (The supply ships were expected before that time.) Told that his answer was unacceptable and that Beauregard would open fire in one hour, Anderson shook the hands of the messengers and said in parting, "If we do not meet again in this world, I hope we may meet in the better one." At 4:30 A.M. on April 12, 1861, 43 Confederate guns in a ring around Fort Sumter began the bombardment that initiated the bloodiest war in American history." '
http://www.us-civilwar.com/sumter.htm

Don says:
'Nor was the Revolutionary War a "pre-emptive war." '
[The Brits had and have a different opinion:]

"After 1769, Washington became a leader in Virginia's opposition to Great Britain's colonial policies. At first he hoped for reconciliation with Britain, although some British policies had touched him personally. Discrimination against colonial military officers had rankled deeply, and British land policies and restrictions on western expansion after 1763 had seriously hindered his plans for western land speculation. In addition, he shared the usual planter's dilemma in being continually in debt to his London agents. As a delegate (1774-75) to the First and Second Continental Congress, Washington did not participate actively in the deliberations, but his presence was undoubtedly a stabilizing influence. In June 1775 he was Congress's unanimous choice as commander in chief of the Continental forces."
http://sc94.ameslab.gov/TOUR/gwash.html