The period following the war 1812 was called the "era of good feelings" because:

the dominoes began to fall. the surrender at appomattox took place a week later on april 9. while it was the most significant surrender to take place during the civil war, gen. robert e. lee, the confederacy's most respected commander, surrendered only his army of northern virginia to union gen. ulysses s. grant

explanation:

the award is named for an american naval historian and theorist, rear admiral alfred thayer mahan, united states navy who, through his writing, provided stimulus and guidance to those who share in the defense of the nation.