Although Andrew Johnson's presidency was marked by significant chaos and administrative ineptitude on the home front, Secretary of State William H. Seward ably managed its foreign affairs. In 1866, the Russian minister to the United States indicated that Czar Alexander II might be willing to sell Russian holdings in North America—nearly 500,000 square miles. Seward offered $7.2 million, which was two cents an acre, and the Russians accepted, transferring land that would become Alaska to the United States.

The treaty of sale differed from earlier territory arrangements by not promising eventual statehood. Its inhabitants—except for Indians—would become American citizens immediately, but it left open the question of statehood, thus relegating the new territory to the status of a colonial possession. Some critics ridiculed the purchase as a frozen, worthless wasteland, as "Seward's Folly." But the Senate embraced the sale with enthusiasm. Charles Sumner, chairman of the Senate Foreign Relations Committee, viewed the purchase as a step leading toward the ultimate possession of Canada. Seward himself wanted the United States to annex much of the Northern Hemisphere, but he was unable to gain Senate consent to acquire the Virgin Islands, Hawaii, Cuba, Puerto Rico, Greenland, or Iceland.

Forcing the French from Mexico

At the end of the Civil War, Mexico was embroiled in war. A French army had occupied key parts of Mexico in 1861, installing a puppet ruler, Archduke Maximilian of Austria, as emperor. The Mexican government, led by Benito Juárez, resisted the forces of Napoleon III who was trying to install the archduke yet had little decisive effect. As soon as the American Civil War ended, Secretary of State Seward sent 50,000 battle-tested U.S. soldiers to the Mexican border to back up his demand that Napoleon withdraw all of his forces. Napoleon agreed, and the last French soldier left in 1867. Although the Monroe Doctrine was never mentioned by name, the confrontation reinforced its hold on American foreign policy.

Relations with Great Britain

During the Johnson presidency, the bumpy U.S. relations with Great Britain were repaired. Johnson tamped down a crisis by enforcing neutrality laws against Irish American Fenians, who made several armed attacks in Canada in an attempt to annex Canadian territory, then controlled by Britain. Civil War claims against the British for building Confederate warships that had sunk Union shipping were sent to arbitration.