The war led to some complications in the foreign relations of the United States. Both in England and France there were statesmen who were jealous of the rapid growth of this country. They were afraid that the United States would become more powerful than their own countries, and they would have been pleased to see it divided. In 1861 this hostile feeling in England was very much increased by what is called "the Trent affair." Mason and Slidell were sent as ambassadors from the Confederate States—Mason to England, and Slidell to France. They ran the blockade, getting out of the harbor of Charleston during a dark night, and reached Havana. From Havana they sailed in the Trent, an English steamer. Captain Wilkes, of an American person-of-war, stopped the Trent and took Mason and Slidell from it, carrying them prisoners to the United States. This act produced great excitement in England, and for a while war seemed imminent between the two countries. But, on the demand of Great Britain, the United States surrendered the ambassadors, as improperly captured.

The United States Navy had been rapidly enlarged after the war began. One of its principal duties was to blockade the Southern ports to keep the Confederates from getting arms and other supplies from foreign countries. Many fast-sailing English ships were engaged in running this blockade. These, by the law of nations, were subject to capture by the Union ships, and many were taken, but the high prices paid for the commodities that were got in, justified the risk. These blockade-runners generally entered the Southern ports at night. But, when the chief Southern ports were captured one after another by the navy and the land-forces of the Union, blockade-running was gradually stopped.

The Confederate government could not get much of a navy afloat from ports so well blockaded, but ships were built in England and secretly sent to sea. These received Confederate commissions, and almost succeeded in ruining American commerce. The most famous of these ships, called the "Alabama," was commanded by Captain Raphael Semmes. It was built in England, and it captured in all sixty-seven merchant and whaling ships. In a fight with the United States person-of-war Kearsarge, the Alabama was sunk in the English Channel, June 19, 1864. After the war the United States set up claims against the British government on account of the damages done to American commerce by the Alabama and other Confederate cruisers built in England. The "Alabama claims," as they were called, after years of discussion, were submitted to a court of arbitration which sat in Geneva, Switzerland, in 1872, and condemned England to pay to the United States $15,500,000.

The expenses of the war can never be fully estimated.The United States government borrowed money on interest, by giving bonds to pay after a certain number of years. A large part of this debt has now been paid. But, as another means of borrowing money, "legal-tender notes" were issued; that is, paper bills, which by law could be used to pay debts and taxes, instead of coins. These legal-tender notes were printed on a peculiar green paper, and got the name of "greenbacks." When a great quantity of them had been issued, and the dangers to the government increased, the value of this paper money decreased, until at one time a dollar of it was really worth but half a dollar. However, as the greenbacks were by law good for the payment of debts, they were used instead of the more valuable silver and gold, which for seventeen years disappeared entirely from general use. Long after the war closed, in 1879, the government began to redeem these legal-tender bills in silver and gold.

This was called "the resumption of specie payments." But the fact that gold or silver was to be paid for them had made greenbacks worth as much as coin, and people generally preferred to keep the paper money.

The Confederate government also resorted to loans, which, however, became almost valueless when the success of the Confederacy became doubtful. It also issued a great deal of legal-tender money, which took the place of coin, and declined in value until twenty dollars of it would not buy one of gold. When the Confederacy was overthrown, this money became of no value. The decline in the value of its paper money was one of the greatest difficulties the Confederate government had to contend with in its last years.

To avoid confusion, we have preferred to tell the story of the military operations or the war without mentioning the political affairs of the time. In 1864 the Republican party nominated President Lincoln for re-election, and Andrew Johnson, of Tennessee, a Southern Union person, for Vice President. The Democratic party nominated General George B. McClellan, and for a time it seemed that the discouragement of the Northern people with the long continuance of the war might elect McClellan. But the success of Sherman in taking Atlanta, the capture of the forts near Mobile by the fleet under Farragut, and the successes of the Union armies under Sheridan in the Valley of Virginia, removed all doubt about the result, and Lincoln received all the electoral votes cast except those of Kentucky, Delaware, and New Jersey.

Lincoln began his second term of office in March, 1865, when Sherman was already marching northward through the Carolinas, and when the close of the war was already in sight. When Confederate General Robert E. Lee surrendered, Lincoln's mind was already revolving plans for conciliating those who had been opposed to him, and for restoring the government at the South. But, while the President was sitting with his family in a box at the theatre, John Wilkes Booth, one of a band of conspirators, approached him from behind and shot him, and then leaped to the stage, crying, "Sic semper tyrannis!" which means, "Thus always with tyrants," and escaped. Booth was afterward overtaken, and killed in resisting arrest. Lincoln died on the 15th of April, the day after he was shot; he was deeply mourned, because he had shown himself a person of great wisdom and goodness. Lincoln's assassination was sincerely regretted at the South, also, where his kindliness was coming to be known, and where the people, newly conquered, feared that his death might lead to measures of retaliation.

But the war was closed without acts of mere revenge,and nobody was put to death for a political offense. Jefferson Davis, the President of the Confederacy, who had been captured in Georgia at the close of the war, was arraigned before a court on a charge of high treason. He was confined in Fortress Monroe for two years, when he was released without being tried.