How did Alaska in the United States come from?

During the American Civil War, in order to prevent Britain and other countries from interfering, Lincoln invited Russia, which has a * * * relationship with the enemy, to help out and asked them to enter the American seaport. After the war, Russia thought they were unable to cope with military expenditure. On the American side, the law stipulates that they can't pay the military expenses of other countries, and it is also the two of them who discuss selling the strait, a place where people can neither live nor farm, to the United States as military expenses.

Of course, the later countries naturally vomited blood with anger = =